Use this tag only if your question is about the modern theoretical footing for probability, for example probability spaces, random variables, law of large numbers, and central limit theorems. Use [tag:probability] instead for specific problems and explicit computations. Use [tag:probability-distributions] for specific distribution functions, and consider [tag:stochastic-processes] when appropriate.
The modern theory of probability is formulated using measure-theory. Use this tag if your question either involves the theoretical foundations of probability or you are seeking responses at the level or rigor used in modern probability theory. Examples of subtopics include probability spaces, random-variables, convergence of random-variables, markov-chains, martingales, brownian-motion and other stochastic-processes, applications of famous theorems including the strong and weak laws of large numbers, the central limit theorem, the law of the iterated logarithm, et cetera.