Rapping (also known as emceeing, MCing, spitting, or just rhyming) is the rhythmic spoken delivery of rhymes and wordplay, one of the elements of hip hop music and culture. Rap is NOT a genre a music, but rapping, or MCing is a part of the genre "Hip-Hop". Hip-Hop also consists of graffiti art, DJing, MCing(rapping), and breaking.
Today, almost all mainstream rap has completely sold out to mainstream America. Mainstream rap has NO self expression in it, and does not represent itself well anymore. More and more artists try to get a hit song, rather than express themselves- or a good album. So anyone that thinks "rap" is what they see on TV (Soulja Boy, 50 Cent, etc.) is definately wrong. In fact, most of these shitty rappers don't even represent their DJ. "Bling rap" is BULLSHIT.
Good rap flows, and not just relies on the beat, it works with it. Rap is all about expression, but has been capitalized on as of late, unfortunately. There are some rappers and hip-hop artists that still keep it real though, but almost all of them are underground- if still active.
For all the people that think rappers like "Soulja Boy, 50 Cent, Chingy, and Chamillionaire" are real, you're wrong. That's "Hip-POP", and it sucks. There is no expression in Hip-Pop, but there is always expression from a real Hip-Hop rapper.
For all the people out there that think rap/hip-hop is what they see on TV, and people rapping about their shopping lists or other miscellaneous bullshit- I urge you to listen to some real Hip-Hop MCs.
Some real Hip-Hop/Rap music:
A Tribe Called Quest
De La Soul
The Notorious B.I.G.
People Under the Stairs
Del Tha Funkee Homosapien
Listen to some of that, if you think that Rap has no self expression, or if you know "Rap" from mainstream radio and TV.
If you don't know where to start, I suggest songs like this(my personal tastes):
"Electric Relaxation" by "A Tribe Called Quest"
"Bluebird" by "One Self"
"Graffiti" by "Digable Planets"
"Breakadawn" by "De La Soul"