Based is a sort of philosophy and mindset forwarded by Bay Area rapper Lil B. Lil B was called "based" by childhood friends when doing something deemed dumb or nonsensical as an allusion to "base heads" or crack addicts. Lil B flipped this term into meaning a sort of self-actualized positivity. Being Based entails being optimistic and positive, kind and friendly, and doing what one wants without caring too much about adhering to preconceived social norms or outside opinion.
In music, Lil B's "based freestyles" which have been released continuously since 2009 are stream of consciousness glances into Lil B's strange and hilarious reality. They don't follow conventional rules like rhyming or braggadocio, instead they are often absurd and intentionally strange deconstructions of the genre itself that hang on the edge of self-parody.