Markov chains are fundamental to the theory of stochastic processes, used extensively in various fields such as statistics, economics, and engineering. The model is characterized by its lack of memory, meaning the next state depends only on the current state and not on the sequence of events that preceded it. This simplicity allows Markov chains to model random processes where future states are independent of past states, given the present state. They are widely utilized in areas ranging from predicting stock market trends to natural language processing, where they help in understanding and predicting sequences of words or phrases.

Historical Overview: The concept of the Markov chain was introduced by the Russian mathematician Andrey Markov in 1906. Markov initially developed these chains to study the independence of trials in a stochastic process, and they gained prominence through the 20th century as they proved valuable in a wide array of scientific disciplines.

Key Contributors: Andrey Markov is the primary contributor to the development of Markov chains. His early work laid the foundation for what would become a broad field of study within probability theory. Over the years, the theory has been expanded and applied by numerous mathematicians and scientists across various domains, further refining the concept and exploring its applications in complex systems.