Sometimes you’ve got a song in iTunes whose format you want to change—you might need to convert a big AIFF file before loading it onto your iPad, for example. First, head over to Edit→Preferences (iTunes→Preferences), click the General tab, and then click the Import Settings button. From the Import Using pop-up menu, pick the format you want to convert to and then click OK.

Now, in your iTunes library, select the song you want to convert and choose Advanced→Create MP3 Version (or AIFF, or whatever format you just chose).

If you have a whole folder or disk full of potential converts, hold down the Shift (Option) key as you choose Advanced→Convert to AAC (or your chosen encoding format). A window pops up so you can navigate to the folder or disk holding the files you want to convert. iTunes won’t convert protected media—Audible.com tracks and older tracks from the iTunes Store that still have copy-protection built in. If you bought a song after April 2009, though, odds are you’re delightfully free of such restrictions, since that’s when Apple stopped copy-protecting music.