A random variable is a fundamental concept in statistics and probability theory that represents the outcomes of random processes or experiments in numerical form. It is essentially a function that assigns a real number to each possible outcome in a sample space. Random variables can be classified into two main types: discrete and continuous. Discrete random variables take on a countable number of values, while continuous random variables can assume an infinite number of values within a given range. Understanding random variables is crucial for analyzing uncertainty and making predictions based on probabilistic models.