In popular use: the universe keeping receipts. In the texts: something heavier and stranger.
Documented
Action, not payback
Karman is the Sanskrit word for act or deed. The Upanishads build the doctrine: action leaves residue that carries across lives, and liberation means escaping the ledger entirely, not winning it.
Assessment: Documented in the earliest texts. The doctrine is about bondage and release, not cosmic customer service.
Stories
Instant karma
The popular version: do good, get goods; cut someone off in traffic, step on Lego by Friday. John Lennon put the phrase on a single in 1970 and the remix never stopped charting.
Assessment: A genuine folk theology, younger than the electric guitar. It borrows the word's authority and none of its mechanics.
Interesting claims
The ledger has no favorites
The correction from within the tradition: karma is not a reward system but a causal one, and in several classical readings even good karma is still chain, gold links instead of iron.
Assessment: Documented in the philosophical schools. The word's pop career is its second incarnation, and not the one it wanted.
Sources and further reading
Brihadaranyaka Upanishad 4.4.5, the action doctrine
Monier-Williams, karman entry
Obeyesekere on rebirth ethics
Lennon, Instant Karma (1970), for the pop remix
Worth asking
A word about escaping the ledger became a word about trusting the ledger. How does meaning reincarnate?