Every laptop, from a netbook to a desktop replacement, includes wireless networking. The standard you're most likely to encounter in coffee shops and airports is 802.11g Wi-Fi, and you can't find a laptop these days that doesn't include 802.11b/g support (802.11b is an older, slower networking standard that you don't see much these days). That's the good news.
The bad news? Even though the faster, less error-prone 802.11n networking standard is quickly finding its way into homes and Wi-Fi hotspots all over, not all laptops being sold today support this standard. It's a good idea to make sure that your new laptop has 802.11n networking if you want it to be future-proof, or if you want to take advantage of the 802.11n wireless you may already have in your home. Fortunately, 802.11n-capable laptops can still connect to 802.11g Wi-Fi just fine, and 802.11n hotspots almost universally allow 802.11g devices to connect; your connection will simply be slower than it could be.
If you need to plug your computer into a wired network, ensure that the laptop you buy has an ethernet jack. Most do, but a few netbooks don't. The standard now is gigabit ethernet, but while some laptops may have slower ethernet jacks (limited to 100 megabits per second), it isn't a major concern. Unless you need gigabit speed to transfer lots of very large files and you're sure you'll be plugging into a gigabit wired network, you don't need to look for that feature specifically.
Many laptops also offer Bluetooth connectivity, which is useful for making use of Bluetooth mice, keyboards, and headsets, or for syncing contacts and calendar information with a Bluetooth phone.
If you want to connect on the go but no Wi-Fi hotspot is available nearby, you'll need a mobile broadband radio. You can buy one as an add-on card, but many laptops offer built-in mobile broadband radios as an option. Typically these are tied to a single wireless carrier (AT&T, Sprint, or Verizon, for example) and require a mobile data plan to use. If you constantly use your laptop on the road, it can be a convenient option. Some netbooks are available from wireless carriers at subsidized prices along with a wireless data plan, but we don't recommend taking this option--the money you initially save isn't worth being locked into a contract for a couple of years.
Most all-purpose and desktop replacement laptops include an optical drive, while most netbooks do not; with ultraportables, it's hit-and-miss. All optical drives in laptops these days will play and burn DVDs. Some laptops even include (or offer the option to add) a drive that can play Blu-ray media and burn DVDs and CDs, which means you can use these models to watch high-def movies. Blu-ray Disc writers--which burn to those high-def discs as well as to DVDs and CDs--remain less common in laptops, and are a more expensive upgrade than the Blu-ray-reader/DVD-and-CD-burner combo. Don't worry too much about the performance ratings on optical drives (expressed, for example, as 8X) unless you plan to do a lot of disc burning.
If you have software on CD or DVD that you need to install, or if you want to watch a movie on disc, you can buy an external DVD drive that plugs into the USB port on your laptop. You don't have to buy the drive from the manufacturer of your notebook. Look for a drive that's "bus-powered"--this means that the drive can get its power from the laptop's USB bus, and shouldn't need a dedicated power adapter.
Hard-drive space on a laptop is just as precious as it is on a desktop PC. Netbooks and ultraportables typically don't offer more than 250GB of storage, while all-purpose and desktop-replacement laptops can have 500GB or more (laptop hard drives are available in capacities up to 1TB, but not all laptops can accommodate the higher-capacity, physically larger 1TB drives sold today). You'll see drives listed as 4200 rpm, 5400 rpm, or 7200 rpm, a measure of how fast the platters spin, in revolutions per minute. Generally speaking, the speedier drives have faster data transfer rates and seek times, which means better file copying, application launching, and boot-up speed. If you plan to store a lot of photos, music, or video on your laptop (or if you intend to install a lot of big games), you'll want as much hard-disk storage capacity as you can get. Some desktop-replacement laptops offer dual-hard-drive configurations.
Some laptop models provide an option for using an SSD, or solid-state drive, instead of a standard hard drive. SSDs tend to cost more (adding hundreds of dollars to the cost of the laptop) and offer far less space than the regular rotating magnetic media type, but they're usually faster and far more durable since they have no moving parts. Some SSDs are even more power-efficient than regular hard drives. SSDs can be a good idea for anyone especially concerned with performance or durability, but you'll pay a lot more money for a lot less storage capacity.
For more information: To get an idea of which laptop category best suits your needs, be sure to read "Laptop Buying Guide: Selecting the Right Laptop for You." And for buying advice, see our handy "Laptop Buying Guide: Shopping Tips" list.