Randomness

A process whose individual outcomes aren't predictable in advance, even though its long-run pattern of outcomes can be described precisely.

Established Supported by convergent, high-quality evidence.

A process is random if its individual outcomes can’t be predicted in advance with certainty, even when the process as a whole follows precise, describable rules — a fair coin toss is random, but “heads comes up about half the time over many tosses” is a fully lawful, predictable statement about that same random process.

Random does not mean patternless: genuinely random sequences reliably produce streaks, clusters, and runs (see clustering and runs) that people often mistake for evidence of a hidden order. Confusing “this doesn’t look random to me” with “this isn’t random” is one of the most common ways a coincidence gets over-interpreted.