By DAVID POGUE

What’s an ultra book?

It’s an absolutely gorgeous, sleek wedge of a laptop, clad in shining brushed metal. There’s no DVD drive. The battery is sealed and nonremovable. The keys protrude through individual square holes in the laptop’s deck. The multitouch trackpad is buttonless — you get different clicks by pressing different spots. You generally need a separate adapter dongle if you want to connect to Ethernet or a VGA projector.

And there’s no hard drive. Instead, you get a solid-state drive (SSD), which is like a giant memory card. It helps with battery life and fast start-up times.

Those expensive SSDs make ultrabooks ultra-expensive ($900 and up), and you get very little storage, usually 128 gigabytes. In a laptop with a regular hard drive, you can get eight times that storage, for a lot less money.

So what is an ultrabook? It’s MacBook Air that runs Windows.

That’s just about everybody’s description — except Intel, which developed the concept. (“Was the MacBook Air an inspiration for this category?” I asked Intel’s P.R. team. “No,” was the answer. “The Ultrabook category was conceptualized out of multiple rounds of research going back several years.” Chalk up one for mind-blowing coincidence.)

Because of the tiny storage, an ultrabook doesn’t make a good primary computer, and can store only wee photo, music and video collections. Forget high-horsepower games, too. And to install non-downloadable software, you’ll have to buy an external DVD drive.

But never mind all that. If you have the money, you’ll love how satisfying, beautiful and exquisitely designed these machines made by the major PC makers are. For most uses — e-mail, Web surfing, chat, Microsoft Office, music, streaming movies — an ultrabook is pure joy. If you can stop running your hands over the cool, polished metal.

A MacBook Air still has the best combination of design, screen, keyboard, trackpad and battery life. But ultrabooks come close, and they offer the advantages of choice. For example, ultrabooks come in larger screen sizes, like 14 inches (Hewlett-Packard) and 15 (Samsung). You can buy one with a nonglossy screen — the colors aren’t as vibrant, but you don’t get annoying reflections. Most ultrabooks have dedicated keys that Apple leaves out, like Home, End, Page Up and Page Down.

Finally, most ultrabooks cost less than an Air, which is $1,300 for the 13-inch model.

I tested ultrabooks from Acer, Asus, Dell, Hewlett-Packard, Lenovo, Samsung and Toshiba. Most have identical guts: 4GB memory, 128GB SSD, Intel Core i5 processor, 13-inch glossy screen (1366 x 768 pixels), an SD slot for your camera’s memory card, two or three USB jacks (including a USB 3.0 for faster charging of gadgets), a miniature HDMI jack for connecting to a TV, Web camera, mike/headphone jacks and illuminated keys. Most weigh just under three pounds and get about six hours on a charge. In most cases, you can pay more for a bigger SSD (256 gigabytes) and faster Intel i7 processor.

Despite those similarities, they have personalities all their own.

ACER ASPIRE S3 ($800). You read that price right: this is the least expensive ultrabook so far.

To reach that price, Acer kind of cheated. The SSD is small (20GB) and holds only start-up files; all your files go onto a 320GB hard drive. Result: lower price, more storage, slower laptop.

More compromises: The keys feel like you’re typing on concrete. The cursor keys are the size of Tic Tacs. Also, only the top is metal (a gorgeous muted silver). The keyboard, deck, palm rest and bottom are all plastic. The battery life isn’t great — about five hours.

ASUS ZENBOOK UX31E ($900). Gorgeous dark gray metal lid, Bang & Olufsen circuitry for slightly richer sound. But the keyboard doesn’t light up, and the keys don’t travel much. You press the left and right lower corners of the trackpad to produce right- and left-clicks, but mine often produced the wrong kind of click.

The screen has higher resolution than most (1600 x 900), meaning that you can see more without scrolling (at smaller size). An 11-inch model is also available.

DELL XPS 13 ($1,000). “Dell” and “gorgeous” don’t generally appear in the same sentence. But the aluminum top, carbon fiber bottom and satisfying keyboard make this ultrabook a look-and-feel triumph. It’s thicker than most ultrabooks, but a whole inch shallower, so you can still work when the joker in front of you reclines his airplane seat.

Sadly, there’s no memory-card slot, HDMI port, navigation keys or Ethernet jack (you can buy an Ethernet dongle). The trackpad never misses your clicks, but its multitouch response is flaky.

LENOVO IDEAPAD U300S ($1,050). This solid, thin, exquisitely engineered black beauty doesn’t taper from front to back; instead, the top and bottom panels (available in charcoal or orange) protrude slightly, like the covers of a book. This machine is unbelievably pleasurable to use.

Typing feels great; some engineer gave each keystroke just the right amount of movement and click. The trackpad is also superb.

Only two omissions mar the perfection: no memory-card slot and no Ethernet jack. Otherwise: Mmmm.

SAMSUNG NOTEBOOK SERIES 9 ($1,400). The black aluminum-alloy lid feels incredibly silky; just touching it is good for the soul. The screen is bright and vibrant — and it’s nonglossy. Thumbs-up on the keyboard, trackpad, weight (2.5 pounds) and battery. The only heartbreaker is the nosebleed pricetag. (Be careful to distinguish it from the 2011 model, which now goes for $970 and includes only a micro-SD slot.)

I tried out the 15-inch model (coming in late April for $1,500): maybe the thinnest, most luscious-looking, most expensive 15-inch laptop ever. Thanks to its 8GB of memory, you might be able to get away with simple video editing — a good use for that vast screen.

TOSHIBA PORTÉGÉ Z830 ($1,150). This laptop is a delightful outlier for four reasons. First, it’s the world’s lightest ultrabook. It even feels a little hollow, and the screen flexes like a piece of shirt cardboard — but at 2.47 pounds, it practically needs a paperweight.

Second, it’s the only ultrabook with a full suite of full-size jacks. There’s a real Ethernet socket, a real VGA port for projectors, a real HDMI port for TV sets. You even get an extra USB socket (three in all). How great not to have to pack a bunch of dumb little dongles!

Third, there are dedicated buttons beneath the trackpad. They’re plastic chrome fingerprint magnets, but at least they never miss a click.

Finally, this model has 6GB of memory instead of 4 — thanks, Tosh! (Best Buy’s version, the Z835, costs only $850. It has a slower chip and only 4GB of memory, but what a deal!)

HEWLETT-PACKARD ENVY 14 SPECTRE ($1,400). Glass, baby. Nearly this entire laptop — lid, screen, keyboard deck — is covered with Gorilla glass, the supertough glass of iPhones and iPads.

That bold, original, shiny, fingerprinty design makes this laptop much heavier than most (3.8 pounds). And pricier. But you get full-size Ethernet and HDMI ports, a glorious screen (1600 x 900), good sound, very good keyboard and one of the best Windows trackpads ever. Free copies of Photoshop Elements and Premiere Elements take the sting out of the price.

(The price-conscious may be more interested in H.P.’s more conventional ultrabook, the $900 Folio, notable for its astonishing 8-hour battery life.)

If you like the ultrabook concept, you’ll love the Lenovo and Dell for getting all of the essentials right; the Samsung for its screen and materials; or the lighter-than-Air Toshiba.

But if you wait, more goodness is coming. The fall crop will bring faster Intel chips and, in some cases, touch screens and Windows 8.

Either way, an ultrabook can bring you many pleasures. Starting with the day it arrives, when the delivery guy slips it under the door.