You've spent months, years, decades updating your music collection from vinyl to 8-track, from 8-track to cassette, from cassette to CD, from CD to this new-fangled digital format. Don't let all that hard work disappear with one fried circuit—back it up.  Open iTunes, under File, choose Back Up To Disk, choose one of the three options given depending on what your needs are. When prompted to do so, insert a blank CD or DVD into the drive. Wait until the disc is finished burning and insert new discs if prompted until your entire library is burned. Store the completed discs, remember they are for restorative purposes only - they cannot be played.