Bit

A bit is the amount of information in a single binary choice, one answer to a perfectly balanced yes-or-no question. Two bits distinguish four possibilities, three bits eight, and so on. It is the atom that all of information theory is measured in.

When we say a task carries a certain amount of uncertainty, or that a document adds so much to an answer, the honest unit underneath is bits. It is what turns 'this feels uncertain' into a quantity you can count.