But just how good is Chrome? How does it differ from IE and from less popular, but still important, browsers like Mozilla’s Firefox and Apple’s Safari?

I’ve been testing Chrome for about a week, trying out all its features and using it side by side with Microsoft’s latest iteration of IE, which came out just last week.

My verdict: Chrome is a smart, innovative browser that, in many common scenarios, will make using the Web faster, easier and less frustrating. But this first version — which is just a beta, or test, release — is rough around the edges and lacks some common browser features Google plans to add later. These omissions include a way to manage bookmarks, a command for emailing links and pages directly from the browser, and even a progress bar to show how much of a Web page has loaded.

Chrome’s interface has some bold changes from the standard browser design. These new features enhance the Web experience, but they will require some adjustment on the part of users. For instance, Chrome does away with most menus and toolbar icons to give maximum screen space for the Web pages themselves. Also, Google has merged the address bar, where you type in Web addresses, with the search box, where you type in search terms. This unified feature is called the Omnibox.

One striking difference in Chrome is how it handles tabs, which display a single Web page. In Chrome, each tab behaves as a separate browser. The bookmarks bar, Omnibox, menus and toolbar icons are located inside the tab, rather than atop the entire browser. The tabs appear at the top of the computer screen. Chrome also groups related tabs. If you open a new tab from a link in a page that’s already open, that new tab appears next to the originating page, rather than at the end of the row of tabs.

Despite Google’s claims that Chrome is fast, it was notably slower in my tests at the common task of launching Web pages than either Firefox or Safari. However, it proved faster than the latest version of IE — also a beta version — called IE8.

Meanwhile, Microsoft hasn’t been sitting still. The second beta version of IE8 is the best edition of Internet Explorer in years. It is packed with new features of its own, some of which are similar to those in Chrome, and some of which, in my view, top Chrome’s features.

Google’s Chrome browser displays thumbnails of a user’s most-visited pages when a new tab is opened, rather than a blank page.

For example, while IE8 also groups related tabs, it assigns a different color to each such tab group and allows you to close them all with one click. It has a “smart” address box of its own, that drops down a list of suggestions as you type, though it retains a separate search box.

IE8 also has breakthrough privacy features that exceed Chrome’s, and includes a new technology called Accelerators, which allows you to take rapid action on any selected word or phrase on a Web page, such as generating a map for a place name, without switching to a new page.

As they develop, each of these browsers has a good chance of besting Firefox 3.0, which I have regarded as the best Web browser for Windows, the only operating system on which Chrome currently runs. But they will have to get faster at loading pages. And, to best Firefox on the Macintosh, Google will have to make good on its promise to produce a Mac version of Chrome, something it says it will do in the coming months. Microsoft has no plans to produce a Mac version of IE8.

Chrome and IE8 are far more advanced than Apple’s Safari. Safari is speedy on both Mac and Windows platforms, but lacks many of the key intelligent features of its newer Google and Microsoft rivals.

Why is Google igniting a new browser war? There are two main reasons, and both involve competing with Microsoft. First, the search giant fears that because its search engine and other major products depend on the browser, Microsoft — with its rival online products — might be able to gain an advantage by altering the design of IE, which has roughly a 75% market share.

Second, and more important, Google sees the Web as a platform for the software programs, or applications, that currently run directly on computer operating systems, notably Microsoft’s Windows. It says current browsers lack the underlying architecture to enable future, more powerful Web applications that will rely more heavily on a common Web programming language called JavaScript. Chrome was designed to be the world’s speediest browser at handling JavaScript.

That move might one day make Chrome a sort of online operating system that competes with Windows. “Think of Chrome as more than a simple Web browser,” Google declares. “It’s a platform for running Web applications.”

Microsoft’s IE8 has an “Accelerator” feature that lets users select any Web text and then map, translate, search or email their selection without leaving the page.

I tested Chrome, and IE8, on a plain-vanilla Lenovo ThinkPad laptop running Windows XP, and equipped with a modest processor and one gigabyte of memory.

To gauge Chrome’s speed at loading Web pages, I launched two large groups of typical Web pages simultaneously, each site opening in its own tab. One group included 15 sports sites, the second 19 news sites. In both tests, Chrome’s speed fell in the middle, at 35 and 44 seconds, respectively. IE8 was slower, taking 49 and 75 seconds to open the two groups of sites. But Firefox and Safari were much faster, notching identical speeds of 19 seconds for the 15 sites and 28 seconds for the 19 sites.

Google claims that future, more sophisticated Web applications relying more heavily on JavaScript than today’s sites do would run faster on Chrome. Of course, I couldn’t test any claim about future scenarios, but I did run Chrome on several JavaScript test sites, used by developers. It handily beat the other browsers. However, Google doesn’t claim users would see much difference on current Web application sites.

I also tested Chrome’s compatibility with scores of common Web sites. In general, it did well, rendering the sites properly. But I ran into problems with video. Some video sites refused to recognize Chrome, because its development has been a secret. On others, like Major League Baseball’s site, videos mostly played properly, but sometimes didn’t.

IE8 also has some compatibility issues, for different reasons. It’s the first version of Internet Explorer to hew closely to Web standards. Earlier versions used some nonstandard ways of rendering Web sites, prompting some site designers to adopt techniques that made their pages work in IE, but look odd in Firefox and Safari. Now, ironically, these pages also look strange in IE8. So Microsoft was forced to build in a special Compatibility View button that users must click to see the sites properly.

Chrome is built on three core design principles. The first is its spare user interface: just two menus and a handful of toolbar icons. IE introduced a similar approach in its version 7, but with a difference. Microsoft allows users to restore a traditional menu bar; Google doesn’t. The only toolbar icon you can add in Chrome is a Home button.

The second principle is that a user can type anything into a single place, the Omnibox, and instantly get suggestions on where to go, gleaned from the user’s own browsing history and Google’s rankings of popular sites. Whether you type in a Web address or a search term, the Omnibox is very smart. In my tests, it sometimes came up with the right destination after I typed only one or two letters of the name of a site I often visited.

The Omnibox has another cool feature: Tab-to-Search. If you type in the name of another site that includes its own search feature, like Amazon.com, the Omnibox lets you just press the tab key to search within that site, without opening it first. Chrome, through its Options settings, also lets you change the default search engine used by the Omnibox. Instead of Google’s own search service, you can use Microsoft’s Live search, Yahoo search, or others.

The third big principle behind Chrome is that each tab runs, under the hood, as a separate browser. Tabs can be dragged off the main browser and turned into separate windows. If one tab crashes, the rest of the browser keeps running. But this doesn’t work perfectly. In my tests, all of Chrome died on me when I tried watching an Olympics video on the NBC site.

You can even make a tab a standalone application that runs from the Start Menu, or the desktop, as if it was a separate program.

Chrome has a few other key features. When you open a new tab, you don’t get a blank page, but a set of thumbnails for your most-visited pages, plus lists of recent search engines you’ve used, recently used bookmarks and recently closed tabs.

Like other browsers, Chrome puts up a warning when you try to visit a malicious or phony Web site, and it has a private browsing mode, called Incognito, which allows you to browse without leaving any history on your computer — a feature popularized in Safari.

Chrome also has a pop-up blocker, but it’s annoying because it flashes a notice that a pop-up has been blocked. IE also does this, but unlike in Chrome, the warnings are much less intrusive.

Internet Explorer 8 has some new features Chrome lacks. Its private browsing mode, called InPrivate, is the first I’ve seen that not only leaves no traces on your own computer, but also bars Web sites from collecting some types of information on where you’ve previously been surfing.

While IE8’s address box and search box remain separate, each also offers rapid suggestions; and both are organized better than Chrome’s. For instance, the suggestions that drop down from its address bar are divided neatly into categories drawn from the browser’s own guess, your history and your favorites. One downside: For this to work in Windows XP, you must first install Microsoft’s desktop search product.

Like Chrome, IE8 lets you switch your default search provider, but it also allows you to switch search engines on the fly. When you type in a search term, icons for alternate search engines appear at the bottom of the suggestion list, and you need only click on these to see search results from, say, Google, instead of Microsoft’s own Live search engine.

IE8’s Accelerators feature presents a blue-arrow icon above any text on a Web page that you have selected. Clicking on the icon brings up a list of actions you can take using the selected text, such as posting it to a blog, emailing it, mapping it or searching it. While these actions are set by default to use Microsoft’s own Web services, you can change them to use Google’s, Yahoo’s, or those from other companies.

Microsoft also has built in a feature called Web Slices. These are portions of a Web site that a site developer can designate to appear in the IE8 Favorites bar and to constantly update themselves. An example might be bidding on eBay.

Like Chrome, IE8 also displays useful information whenever you create a new tab, including a list of recently closed tabs and a list of Accelerators.

With the emergence of Chrome, consumers have a new and innovative browser choice, and with IE8, the new browser war is sure to be a worthy contest.

Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

So it was a big deal when Apple (AAPL) announced a new service that, for $100 a year, would bring corporate-type synchronization of email, calendars and contacts to anyone. It was even better that Apple promised that the service, called MobileMe, would work on Windows computers as well as on the company’s own Macintosh computers, iPhones and iPod Touch hand-helds. To top it off, Apple threw in 20 gigabytes of online storage, a suite of Web-based applications, the ability to synchronize browser bookmarks and an online photo gallery.

Unfortunately, after a week of intense testing of the service, I can’t recommend it, at least not in its current state. It’s a great idea, but, as of now, MobileMe has too many flaws to keep its promises.

I am not referring to the launch glitches that plagued MobileMe earlier this month, such as servers that couldn’t keep up with the traffic and email outages that, for some users, persist as I write this. Those were bad, but they have eased considerably. Apple already has apologized for them and is giving customers an extra 30 days on their subscriptions to make up for the poor start. The problems I am citing are systemic.

Here’s how it’s supposed to work. You subscribe to MobileMe and set up a new MobileMe email account, which can also suck in email from your current address. Your MobileMe email is pushed to your Windows computer using your choice of Microsoft (MSFT) Outlook, Outlook Express or the new Windows Mail program. It’s also pushed to your Mac using the built-in Apple Mail program. And it shows up instantly on your iPhone in the phone’s built-in email program.

Similarly, if you add, delete or change a calendar entry or a contact on any of the devices, the change automatically is reflected on all the others. In Windows, the MobileMe calendar shows up in Outlook, and the contacts can be viewed in Outlook, the Windows Address Book or Windows Contacts. On the Mac, the calendar and contacts appear in the built-in iCal and Address Book programs. On the iPhone, MobileMe uses the built-in Contacts and Calendar programs.

Bookmarks can be synchronized using either the Mac or Windows versions of Apple’s Safari Web browser, or Internet Explorer 7 on Windows.

At the MobileMe Web site, using any computer, you can send and receive email via a Web-mail program, and view and edit your calendar and contacts. Changes made on the Web site instantly show up on your computers and your iPhone, and vice versa. Also at the MobileMe Web site, you can maintain a photo gallery and view your online file storage.

But in my tests, using two Macs, two Dell (DELL) computers and two iPhones, I ran into problem after problem. One big issue is that while changes made on the Web site or the iPhone are instantly pushed to the computers, changes made on computers are only synced every 15 minutes, at best. Apple has admitted that this is a problem, and says it is working on it.

But there’s more. The Web site was sluggish, and occasionally calendar entries wouldn’t load at all. Sometimes, you have to manually refresh the Web pages to see changes made on your devices. And when I tried to open my Web-based file-storage page directly from the MobileMe control panel on Windows, I got an error message on both Dells.

My MobileMe calendar, which originated on a Mac, didn’t flow into the main Outlook calendar, but appeared as a separate calendar in Outlook, which was visible only by changing settings. My address-book groups on the Mac, which are simply distribution lists, didn’t show up as distribution lists in Outlook, but as separate address books, and they also weren’t immediately visible. Apple blames Outlook quirks for these issues, but in my view, it should have overcome them.

Other problems abounded. On one occasion, my synced contacts on the iPhone appeared as names only, without any information. In general, synced contacts on the iPhone loaded slowly.

When my Apple Mail program used rules I had set up to automatically file certain emails into local folders instead of leaving them in the inbox, they simply disappeared from my MobileMe account on the iPhone and the Web site. Avoiding this requires a tedious editing of all your rules.

Twice, MobileMe was unable to sync my bookmarks at all, and when it did, their order was scrambled. When I synced contacts to my iPhone, my custom ringtones for particular contacts were lost and had to be reselected.

Apple patiently explained each of my problems, sometimes helping me with workarounds, sometimes claiming they were rare, other times saying that it was working on fixes.

If Apple does get MobileMe working smoothly, it could be a terrific service. But it’s way too ragged now.

• Find all of Walt Mossberg’s columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com. Email him at mossberg@wsj.com.

That is the question that Mozilla, the nonprofit organization that makes the leading alternative browser, hopes to answer this month when it releases version 3.0 of its Firefox Web browser. In some tech-industry circles, Firefox already is preferred over Microsoft’s (MSFT) Internet Explorer and Apple’s (AAPL) Safari, but it still isn’t used by most people, and Mozilla is hoping to broaden its appeal.

The new version will be released simultaneously for Windows and the Mac’s OS X operating system, as well as for Linux. While each of the three editions will have the visual style of the operating system on which it runs, all three will have the same features.

I’ve been using prerelease versions of Firefox 3.0 for months, and have recently been testing a near-final version and comparing it closely to IE and to Safari. I have tested it on multiple Windows PCs and Macs, on desktops and laptops, over slow connections and fast ones. I have tried it with well over 100 Web sites.

My verdict is that Firefox 3.0 is the best Web browser out there right now, and that it tops the current versions of both IE and Safari in features, speed and security. It is easy to install and easy to use, even for a mainstream, non-technical user. It can be downloaded, free, at mozilla.com by clicking on “Firefox 3 Sneak Peek.”

This situation may change. Microsoft is working on a new version of IE, scheduled to be unveiled later this year, with some impressive new features. And Apple is always working on new iterations of Safari, though it is secretive and hasn’t disclosed its plans. But for now, in my view, Firefox 3.0 rules on both Windows and Mac.

I couldn’t find any significant downsides to Firefox 3.0. Every page I tried rendered properly and rapidly on both platforms. I ran into only one glitch, in a preference setting. That problem appeared on only one of my four test machines and was fixable with the help of Mozilla, albeit via a geeky method.

In the one or two cases where Firefox lacked a feature I thought important, such as the “auto fill” feature in Safari that can quickly fill out an online form, I was able to find an add-on that did the trick from Mozilla’s vast library of add-ons, which are written by people all over the world. (One caution: Some existing add-ons won’t work with the new version until their authors update them.)

When Firefox first came out, it was the fastest browser, but it lost that title over the years. However, in my tests, this new third version of Firefox regained the speed crown. It beat IE 7 handily on my test Windows computers and edged Safari slightly on my test Macs.

For example, using a new Dell (DELL) XPS One desktop, I opened identical folders containing the same 16 bookmarks on both IE 7 and Firefox 3.0. IE took 37 seconds to completely display the 16 pages, but the new Firefox did it in just 23 seconds. On a new Apple iMac, I did a similar, but more daunting, test — opening identical folders containing 24 bookmarks. Safari rendered all of the pages in 36 seconds, but the new Firefox finished the job in 32 seconds.

The latest Firefox has a number of new and improved features. If you type any word or phrase into its address bar, the browser instantly searches your history and bookmarks for a possible match, to save you from typing or combing through your bookmark list.

The whole process of managing bookmarks has been vastly simplified. Every Web address is accompanied by a star icon at the right. To bookmark the site, you just click the star once. No other action is required. To specify where to file the bookmark, you click the star twice. You also can remove bookmarks by clicking the star. And you can tag bookmarks with key words, to make it easier to find them.

There are also smart bookmark folders, which gather your most visited sites, or most recently bookmarked sites, automatically into folders. You also now can more easily back up and restore your bookmarks, complete with tags.

Security is also improved. The old version of Firefox would warn you when a site you were visiting appeared to be a fake, designed to steal your identity. (IE has a similar feature, though Safari doesn’t.) But Firefox 3.0 now warns you about sites that are known for trying to plant viruses, spyware and other malicious software on your computer, a warning the other big browsers don’t yet provide.

With one click, Firefox 3.0 also provides details about who owns the site you’re visiting, and whether it’s encrypted, if the site owner has adopted a special type of security certificate.

My bottom line: Even though you already have a built-in browser, Firefox 3.0 can improve your Web experience.

• Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

These types of attacks are called “social engineering,” and they are used by criminals to steal your money and identity, and to plant on your computer malicious software that can be used to keep ripping you off. Social engineering is the online equivalent of an old-fashioned con game, in which a crook frightens people with false warnings, or tempts them with false promises, and then robs them.

While viruses and spyware overwhelmingly afflict Microsoft’s (MSFT) Windows users and spare users of Apple’s (AAPL) Macintosh computers, social-engineering schemes can ensnare Mac users as well. There’s nothing inherent in Macs that makes their owners more resistant to falling for social-engineering scams.

The most common form of social engineering is called phishing, a one-two punch using both email and Web browsing to trick people into typing confidential information into Web sites that look like the sites of real companies, especially financial institutions. But these phishing sites are actually skillfully designed fakes that transmit your sensitive data to criminals, often in distant countries. Once these creeps have your passwords and account numbers, they can loot your funds and steal your identity.

Here are some tips to help you avoid being the victim of social engineering, updated from a similar column I wrote in 2006. It includes information on some antiphishing software that wasn’t available back then. But remember: Security software alone can’t save you from scams.

1. Never, ever click on a link embedded in an email that appears to come from a financial institution, even if it’s your own bank or brokerage and even if it looks official right down to the logo. The same goes for payment or auction services, like PayPal or eBay (EBAY). Don’t do this even if the email asserts that your account has a problem, or that the bank has to verify your information. And certainly don’t enter any passwords, Social Security numbers or account numbers directly in an email.

These types of emails are almost always fakes, and the links they contain almost always lead to phony Web sites run by criminals. The only exception might be a confirmation email from a brokerage firm concerning a trade you know you made minutes before. Even legitimate-looking addresses in emails or in the address bar of Web browsers can be fakes that hide the crooks’ true Web addresses. The lock icon on a Web site can also be falsified.

If you are truly worried about your account, call the bank or company, or go to its Web site by manually typing in its address or by using a well-established bookmark in your browser that you created yourself.

2. Don’t click on links to offers for free software or goods that you receive in an email, especially from a sender or company you’ve never heard of.

3. Never download software from unfamiliar Web sites unless you are absolutely sure you need it and it’s legitimate. Even if it claims to be a useful program, it may very well be a malicious application like a “key logger,” which can report back to crooks everything you type into your computer. If you really want the program, do a Web search on it first, to see if others have reported it as a malicious fake.

4. If a Web site tells you that you need to download special viewing software to see its videos, don’t do it. Even if it claims to be giving you legitimate viewing software, like Microsoft’s Silverlight, Adobe’s (ADBE) Flash or Apple’s QuickTime, don’t download it there. Go to the official Microsoft, Adobe or Apple Web sites to get these viewers.

5. Use a Web browser, like Internet Explorer 7 on Windows, or Firefox 2.0 on Windows or Mac, that includes built-in features to warn you about, or block access to, known phishing sites. The next versions of these two browsers will have even stronger features that will detect sites that are not only fake, but which are known to distribute malicious software.

Unfortunately, the third major browser, Apple’s otherwise excellent Safari for Mac and Windows, lacks any such antiphishing detection, though I expect Apple to add the feature in a future version. So, for now, Mac users worried about phishing should rely on Firefox.

6. Consider security software that tries to detect and block phishing sites. McAfee’s (MFE) free Site Advisor and paid Site Advisor Plus products do a good job. Symantec (SYMC) has similar features built into its large security suites, Norton 360 2.0 and Norton Internet Security 2008.

7. Educate yourself by reading about social engineering and phishing and how to avoid being a victim. Microsoft has a very good guide at: microsoft.com/protect/yourself/phishing/identify.mspx and Symantec has one at: symantec.com/norton/clubsymantec/library/article.jsp?aid=cs_phishing.

Follow these tips and you’ll be a happier — and safer — surfer.

Find all of Walt Mossberg’s columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

• Email him at mossberg@wsj.com.