This interface is generally called “multitouch,” and it involves using one or more fingers on a screen or touchpad to perform special gestures that manipulate lists or objects on a screen — without moving a mouse, pressing buttons, turning scroll wheels or striking keys.

The best-known example of the interface is on Apple’s iPhone and iPod Touch devices. It allows you, for example, to rapidly flip through photos, lists of emails or song titles by merely “flicking” a fingertip on its screen, or to resize a photo by “pinching” the image with two fingers. And, this month, Apple moved some of these multitouch features onto a laptop, its new MacBook Air, where fingertip actions are performed on an oversized touchpad rather than on a screen.

Apple didn’t invent the multitouch concept. Academic and commercial researchers, and small, obscure companies, have been working on it for years. Apple is adapting the concept, adding its own ideas and popularizing it — just as it did in the 1980s with the mouse and the graphical user interface, which had also been invented elsewhere.

Rival companies are scrambling to add multitouch features to laptops and other digital gadgets. Synaptics, a leading supplier of touchpads for laptop makers who compete with Apple, has announced that shortly it will incorporate several multitouch features into its touchpads. Microsoft is producing a coffee-table-size computer called the Surface, meant for hotels, casinos and retail stores, that uses multitouch finger gestures to move around digital objects such as photos, play games and browse through product options. Hewlett-Packard developed a prototype of a similar multitouch coffee-table computer for home use.

Rotating a photo on Apple’s MacBook Air

And, in the back rooms of this month’s Consumer Electronics Show in Las Vegas, various cellphone makers, seeking to emulate the iPhone, were showing off their own unannounced efforts at multitouch. One prominent cellphone maker, Taiwan-based HTC, has already built a phone, called the Touch, which slaps a rudimentary multitouch interface on Microsoft’s Windows Mobile operating system.

The basic touch screen, of course, is an old and familiar thing. People use them every day to get money from ATMs or to check into flights at airport kiosks. Microsoft’s Tablet computers and Palm’s Treo cellphones, among others, use touch screens that employ styluses or fingers to move cursors, select icons and other items, and even to write on the screen.

But multitouch interfaces are potentially much more versatile. They allow you to use your fingers to manipulate virtual objects on a screen as if they were real, sort of the way Tom Cruise’s character did in the 2002 Steven Spielberg science-fiction film, “Minority Report.” For example, Microsoft’s Surface allows users to rearrange groups of digital photos by just dragging them around on the table top as if they were actual paper prints.

Unlike the touch screens on, say, ATMs, multitouch devices are able to distinguish between the press of a single finger and the press of multiple fingers, and to interpret the motions or gestures you make. They take different actions depending on how many fingers they detect and which gestures a user performs.

On Apple’s MacBook Air, the touchpad still allows you to use one finger to move the cursor and click like a mouse can. But, optionally, it can do much more using multitouch gestures.

You can rotate photos by just touching two fingers to the touchpad and moving the images on the screen as you wish. You can quickly move back and forth through a series of Web pages or photos by “swiping,” or placing three fingers on the touchpad and moving them rapidly sideways. And you can shrink or expand a photo, or zoom in and out on a Web page, by pinching the image.

All recent Mac laptops, not just the new Air, have the optional ability to scroll through a screen without using any button or special zone on the touchpad. You just place two fingers, instead of one, anywhere on the touchpad and drag them across its surface.

In addition to pinching, the new Synaptics touchpads have a feature called “ChiralMotion,” which achieves rapid scrolling by moving two fingers in a circle anywhere on the touchpad. Another Synaptics feature, called Momentum, lets you emulate a trackball by flicking a single finger across the touchpad. This gesture can move an object on screen, like a virtual bowling ball in a game, with the illusion of inertia.

It’s too early to know if the new multitouch approach will ever be as big as the mouse-driven graphical user interface. But it’s already evident that it offers real advantages on devices where a mouse isn’t possible or convenient to use, or the decades-old interface of menus and folders is too cumbersome.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

The new aluminum-clad MacBook Air, which I’ve been testing for several days, is billed as the world’s thinnest notebook computer. Its thickest point measures just three-quarters of an inch, which is slimmer than the thinnest point on some other subnotebooks. And it employs some innovative software features, such as fingertip gestures for its touchpad that are similar to those on Apple’s iPhone.

Apple refused to make the most common compromise computer makers employ to create their littlest laptops. Other subnotebooks — a category generally defined as weighing three pounds or less — have screens of just 10 to 12 inches and compressed keyboards. The three-pound MacBook Air, by contrast, features a 13.3-inch display and a full-size keyboard.

It’s impossible to convey in words just how pleasing and surprising this computer feels in the hand. It’s so svelte when closed that it’s a real shock to discover the big screen and keyboard inside.

But there’s a price for this laptop’s daring design: Apple had to give up some features road warriors consider standard in a subnotebook, and certain of these omissions are radical. Chief among them is the lack of a removable battery. So, while the MacBook Air will be a perfect choice for some travelers, I can’t recommend it for all. It really depends on your style of working on the road and what features you value most.

The MacBook Air, which will be available next week, costs $1,800 with an 80-gigabyte hard drive and a generous two gigabytes of memory. A second model, with a faster, cutting-edge, 64-gigabyte, solid-state drive and a slightly speedier processor, costs a whopping $3,100. The $1,800 price for the main model isn’t unusual in subnotebooks, which can easily top $2,000, although some competitors cost less.

In my tests, the MacBook Air’s screen and keyboard were a pleasure to use. The machine felt speedy, even with multiple programs running. And the laptop has the same Leopard operating system, superior built-in software, and paucity of viruses and spyware that I believe generally give the Mac an edge. I was able to install and run Windows XP using the third-party Parallels software.

But then there are those trade-offs. The sealed-in battery means you can’t carry a spare in case you run out of juice, and you have to bring it to a dealer when you need a new one. There’s no built-in DVD drive. The thin case can’t accommodate a larger internal hard disk. And the machine omits many common ports and connectors.

The MacBook Air

There’s no Ethernet jack for wired broadband Internet connections and no dedicated slot for the most common types of external cellphone modems. That means that out of the box, the MacBook Air has only one way to get on the Internet — through its fast, built-in Wi-Fi connection. If you’re out of Wi-Fi range, you’re out of luck, unless you buy an optional, $30 add-on Ethernet connector or a cellphone modem that connects via USB.

In fact, the MacBook Air has only three connectors: a headphone jack, a single USB port and a port for connecting an external monitor.

That single USB port is a problem, because so many peripherals use USB. You can buy a tiny, cheap USB hub that adds three more ports, but that’s yet another item to carry.

The lack of a DVD drive is partly solved by some clever software Apple included that lets you “borrow” the DVD drive on any other Mac or Windows PC on your network, so you can transfer files or install new software from a CD or DVD. This worked fine in my tests, in which I installed several new programs from CDs on remote computers, but it requires disabling third-party firewalls on Windows machines. It also doesn’t work for installing Windows on your Mac, for watching DVDs, or for playing or importing music. For those tasks, you need an external DVD drive. Apple sells one for $99.

In my standard battery test, where I disable all power-saving features, set the screen brightness at maximum, turn on the Wi-Fi and play an endless loop of music, the MacBook Air’s battery lasted 3 hours, 24 minutes. That means you could likely get 4.5 hours in a normal work pattern, almost the five hours Apple claims.

But the MacBook Air has another downside: its screen height. Because of the larger screen, the lid stands higher when opened than on most other subnotebooks. So it isn’t as usable as some competitors when the seat in front of you in coach on a plane is reclined.

If you value thinness, and a large screen and keyboard in a subnotebook, and don’t watch DVDs on planes or require spare batteries, the MacBook Air might be just the ticket. But if you rely on spare batteries, expect the usual array of ports, or like to play DVDs on planes, this isn’t the computer to buy.

• Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

So, I have steered away from recommending Linux, the free computer operating system that is the darling of many techies and IT managers, and a challenger to Microsoft’s dominant Windows and Apple’s resurgent Macintosh operating system, OS X. Linux, which runs on the same hardware as Windows, has always required much more technical expertise and a yen for tinkering than average users possess.

Lately, however, I’ve received a steady stream of emails from readers urging me to take a look at a variant of Linux called Ubuntu, which, these folks claimed, is finally polished enough for a mainstream user to handle. My interest increased when Dell began to sell a few computer models preloaded with Ubuntu instead of Windows.

I’ve been testing one of those Dell Ubuntu computers, a laptop called the Inspiron 1420N. I evaluated it strictly from the point of view of an average user, someone who wouldn’t want to enter text commands, hunt the Web for drivers and enabling software, or learn a whole new user interface. I focused on Ubuntu and the software programs that come bundled with it, not on the hardware, which is a pretty typical Dell laptop.

My verdict: Even in the relatively slick Ubuntu variation, Linux is still too rough around the edges for the vast majority of computer users. While Ubuntu looks a lot like Windows or Mac OS X, it is full of little complications and hassles that will quickly frustrate most people who just want to use their computers, not maintain or tweak them.

Before every passionate Linux fan attacks that conclusion, let me note that even the folks who make and sell Ubuntu agree with it. Mark Shuttleworth, the South African-born founder of the Ubuntu project, told me this week that “it would be reasonable to say that this is not ready for the mass market.” And Dell’s Web site for its Ubuntu computers warns that these machines are for “for advanced users and tech enthusiasts.”

So, what do I mean when I say Ubuntu is too rough around the edges for average users? Here are some examples.

There is no control panel for adjusting the way the touch pad works, and I found it so sensitive that I was constantly launching programs and opening windows accidentally by touching the thing. Every time the computer awoke from sleep, the volume control software crashed and had to be reloaded.

When I tried to play common audio and video files, such as MP3 songs, I was told I had to first download special files called codecs that are built into Windows and Mac computers. I was warned that some of these codecs might be “bad” or “ugly.”

To get the computer to recognize my Kodak camera and Apple iPod, I had to reboot it several times. When it did find the iPod, it wasn’t able to synchronize with it. Playing videos was a bad experience, with lots of flickering and freezing. Oh, and there’s no built-in software for playing commercial DVDs.

The Ubuntu-equipped Inspiron 1420N starts at $744, but the configuration that Dell lent me for testing sells for $1,415. The same unit equipped with Windows Vista costs $1,524. The Ubuntu version includes OpenOffice, the free office suite that competes with Microsoft Office. Dell charges an added $149 for Microsoft Office.

Ubuntu and other versions of Linux have several advantages. Unlike Windows and OS X, they’re free. Unlike Mac OS X, they can be run on the least-expensive popular hardware configurations. Unlike Windows, but like the Mac, they are essentially free of viruses and spyware. And unlike Windows and Mac OS X, they are built and constantly improved by a world-wide network of developers, professional and amateur — the so-called open-source concept that produced the excellent Firefox Web browser.

It makes sense that all the best software brains can’t be located in just two places: Redmond, Wash., where Microsoft is based, and Cupertino, Calif., Apple’s base. And plenty of people reading this have had lots of frustrations with the two better-known operating systems, especially Windows, whose latest iteration, Vista, is disappointing in many ways.

But open source is a two-edged sword. While it draws on smart developers from many places, nobody is ultimately responsible for the quality of the product, and open-source developers often have an imperfect feel for how average people use software. A European company called Canonical is the “commercial sponsor” of Ubuntu and provides support. But it’s largely focused on corporate and techie users. Average Ubuntu users are likely to have to wade through online forums, often written in technical language, to get help.

Dell and Canonical tell me there are complex workarounds for some of the problems I encountered, and that built-in improvements are planned for others. But for now, I still advise mainstream, nontechnical users to avoid Linux.

Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital web site, http://walt.allthingsd.com.