Chance, counted

A number for “how likely”

A probability is a number between 0 and 1 that says how likely something is. 0 means “never”, 1 means “always”, 0.5 means “half the time”. You can also read it as a fraction of the time: in the long run, an event with probability 0.3 happens in about 30% of tries.

Machine-learning models don’t really give answers — they give probabilities. “90% cat, 8% dog, 2% something else.” “The next word is the with probability 0.21.” So we need to be fluent in them.