Apple on Monday celebrated the fifth anniversary of iTunes (Music Store) with a look at back at all "all of the great music, video, and exclusives" that users discovered on iTunes and highlighting the songs and shows that defined each year. On its iTunes store, Apple offered a brief history along with a collection of "best sellers". The company, which launched the iTunes Store on April 28, 2003, claims grew its music catalog of more than 200,000 songs and a handful of exclusive tracks to more than 10 million, according to info available at the online store -- up 66 percent from the 6 million song catalog announced in early April. Update: As readers point out, the iTunes software was released in 2001. [updated]

Earlier this month, the company announced that the iTunes Store surpassed Wal-Mart to become the number one music retailer in the US based on data from January and February of 2008. Apple also touted that it had served over 50 million customers and sold more than four billion songs.

iTunes accounts for approximately 70 percent of digital music sold worldwide. Wired notes that in the next five years, Apple's media service may well account for a staggering 28 percent of all music sold worldwide.

Citing a report from market research firm Instat, the Wired blogger notes that digital music is projected to account for 40 percent of music sold and that if Apple holds onto its current market share, it will account for more than one-quarter of all music sales by its ninth birthday.

In 2004, the company expanded its music catalog, began offering exclusive content with the first digital boxset: the Complete U2, launched 'iTunes Originals' with sets from Sting and Alanis Morissette, and added audiobooks to the its expanding its collection content beyond music.

In its third year (2005) Apple added TV shows and music videos as well as its Podcast directory and iTunes Essentials, which offers collections of music based on artist, genre, and other themes.

The following year (2006), Apple introduced movies, offering both new releases and library titles for sale. Apple also launched downloadable iPod games and the iTunes Latino Store with music, video, and media dedicated to the Latino culture.

During the last year (2007), the company launched iTunes U with free lectures, lessons, and other academic content as well as custom ringtones and the iTunes WiFi music store alongside the introduction of the iPhone and iPod Touch. The company said it now has a catalog of more than 10 million songs and serves over 22 countries worldwide. It also claims it has delivered over 125 million TV downloads.