If you have watched Dave Chappelle doing his stand-up comedy special on Netflix, you have probably said out loud, "This Stand-up Special is LIT".
The word 'Lit' has been a slang term that meant "intoxicated" but recently, in the present digital culture, it has acquired the meaning "exciting", and a broader meaning which is along the lines of "excellent".
Lit: Old Slang Usage
The earliest meaning of lit was “intoxicated,” and that shows up in English as far back as the 1910s:
We walked into the vamp's house. We all got lit and had a hell of a time. —John McGavock, 1918.
Here, the use of lit suggests something that is illumined or has light shining on it, i.e. it comes from the past tense of the verb light.
When the meaning tried to signify through lit is "drunk", it is still considered slang. It does not have the same purpose as "drunk" does and it can be heard in informal settings, like rap lyrics and normal speech. In fact, the resurgence of this meaning has been due to its use as rap lyrics.
Lit: New Slang Usage
A new meaning of lit is given to us by Rap. lit has transitioned from being applied to the act of intoxicating ("gonna get lit") in the last ten or so years to the environment of those who are lit ("party's lit"). lit has gained the meaning "exciting", by the wildness of such parties as well as a broader meaning along the lines of "excellent". This meaning dates way back to 2004. The extended meaning of lit could be an extended meaning on social media like Twitter.