Do you need an optical drive?
Optical storage mediums have been key computer components since the first CD drives arrived on the scene, but cheap flash storage in the form of USB drives and cloud storage on the Internet have nearly eradicated their necessity. When was the last time you used a CD burner? Do you watch DVDs on your computer, or do you stream movies from Netflix? If you do either of those things regularly, or need to be able to burn DVDs or CDs for work, that's okay -- there are still plenty of laptops outfitted with CD/DVD combo drives. Blu-ray drives are even optional in a small selection of laptops, most commonly the media-focused 15-inch (38-centimeter) and 17-inch (43-centimeter) models.
If you're on the fence about needing a disc drive, educate yourself on cloud storage. Dropbox makes it easy to transfer files between multiple computers. Netflix makes it easy to stream movies and TV shows from the cloud. Spotify, Rdio, iTunes Match and a host of other music services allow you to stream music to your computer as long as you have an Internet connection. And there's always the option of using an external hard drive or flash drive to transfer files from a computer that does have a disc drive.
That brings us to another important consideration: making sure your laptop has all the ports you need.