As you rip a CD, you can have iTunes check the iTunes Store for album art.
The easiest way is to have iTunes do it for you (you’ll need to set up an iTunes Store account if you don’t already have one). To hunt down album art for tracks you’ve ripped yourself, you can employ one of several methods. Here’s how to find, add and work with album art in iTunes.
Album art is both useful and decorative it’s much nicer to see your music with cover art than the boring, default gray musical note graphic. Similarly, you can use Cover Flow in iTunes to scroll through your songs and albums, and iOS devices let you flick through your music in Cover Flow view with your fingertip.
The quickest way to find a CD in a pile of jewel cases is by looking for its familiar cover.