Trivia: In its early days, Shazam was a call-in service, not an app!
It was a call-in service. You read that right — you'd hear a song whose name you'd like to know, and you'd dial 2580 and let Shazam's servers listen to an excerpt of the song (up to 30 seconds-long) and then have them hang up on you. Just like that. Thankfully, this wasn't a scam, and Shazam's computers would then send you an SMS message with the name of the songs, provided they got a hit. Later, in 2004, Shazam also launched in the US on AT&T's network.
It was years later, on the 10th of July 2008 that Shazam launched as an app on the Apple App Store, and then, in October, on the Android Market (the ancestor of the Play Store). It's what we use to this day, though much improved in terms of functionality, success rates, and design.
Funny how things work out, eh?
Things that are NOT allowed: