Let's go from what's inside a typical ultraportable to the most visible aspect of the exterior: the screen. Ultraportables' displays come in an increasingly varied array of resolutions, from now-humdrum 720p (1,366 by 768 pixels) in the very cheapest budget models, to full HD (1,920 by 1,080 pixels) as the mainstream norm, to Ultra HD or 4K (3,840 by 2,160 pixels), with a few nonstandard resolutions peppered between full HD and UHD. Lower-resolution screens are most frequently found in entry-level systems simply because they're the least-expensive option. They work well enough for reading and typing text, and YouTube often defaults to something lower than full HD, anyway, so less discerning users can get by just fine. But a 1,366-by-768-pixel screen is best avoided in a new laptop with a screen 13 inches or larger, if you can help it. Full HD (often referred to as 1080p) screens are what you should expect on many budget systems, all midrange models, and some premium ultraportables. The 1080p display is becoming standard enough that even some cheaper options now offer them, a far cry from the situation just a few years ago when a much grainier 1,366 by 768 was the norm. These displays offer support for full-1080p video playback and are better equipped for multitasking since you can fit more readable text and two side-by-side windows onto a 13- or 14-inch 1080p screen. This is a sharp, true full-HD resolution, ideal for most daily use. Ultra HD is currently the resolution of choice for the highest-end ultraportables and models for content-creation pros. As 4K screens have four times the resolution of a full HD display, you can fit a lot onto them. The sheer number of pixels requires more power, however, and 4K-equipped systems usually see a significant drop in battery life compared with similar full HD systems. You also have the question of content. Although 4K TVs and displays are becoming increasingly common, 4K content streaming is far from universal (this is slowly improving on some streaming services), and gaming in 4K is definitely way more than any ultraportable can support. At present, these displays are best suited to uses like photo and video editing, but they do look stunning. Some premium laptops now use QHD or QHD+ screens, which are resolutions that fall between 1080p and 4K. They represent a nice middle ground between expensive, power-draining 4K resolutions and sharp, better-than-HD picture quality, so you should be happy to see QHD or QHD+ on a laptop you're considering buying. In addition, an increasing number of light-laptop makers have moved their ultraportable models to screens with squarer aspect ratios, such as 16:10 or 3:2, away from the much more common 16:9. That's a trend we saw ramping up a couple of years ago, and it's continuing. Additionally, brilliant OLED display technology is making its way into some of our favorite laptop lines. The other feature to watch for is support for touch input. While touch-capable displays were uncommon just a few years ago, they're now much more of a thing in ultraportables, even in the entry-level and business-laptop categories. Touch technology is useful on a bus or train where you may not have elbow room to use a mouse or touchpad, making it a good match for ultraportables. Even if you don't regularly use touch in your day-to-day computing and don't plan to incorporate it, it may be worth having just so you don't regret the decision not to get it down the road.