Definition and basic structure
The Russian mathematician Andrey Markov first studied these processes in 1906 to show that the law of large numbers can hold for dependent random variables, reportedly to rebut a claim that independence was essential. In a Markov chain, if it rains today there is a fixed probability of rain tomorrow, and that probability does not depend on the weather yesterday or the day before. This is the Markov property, or memorylessness. The probability of moving from one state to another is a transition probability, and the table of them is the transition matrix; multiplying the matrix by itself gives the probabilities several steps ahead. In 1913 Markov counted 20,000 letters of Pushkin's novel Eugene Onegin to estimate how vowels and consonants follow one another, an early application of probability models to language.
Stationary distributions and long-run behavior
A finite Markov chain in which every state can reach every other (irreducibility) and that is not trapped in a fixed cycle (aperiodicity) converges to a unique stationary distribution regardless of where it starts. The stationary distribution gives the long-run fraction of time spent in each state. Kolmogorov (1936) systematized the theory, and texts by Kemeny and Snell (1960) and Norris (1997) became standard. Levin, Peres and Wilmer (2009) surveyed "mixing times," how quickly a chain approaches stationarity. This property is also why MCMC in the Monte Carlo method works: build a chain whose stationary distribution is the target and run it long enough to draw samples from it.
Major applications
In information theory Shannon (1948) modeled English text as a Markov process and generated sample sentences. Hidden Markov models, in which unobserved states follow a Markov chain and only outputs are seen, were founded by Baum and Petrie (1966) and surveyed by Rabiner (1989), becoming core tools in speech recognition and bioinformatics. In economics Hamilton (1989) proposed the Markov-switching model, in which expansions and recessions alternate according to a Markov chain. Brin and Page's (1998) PageRank scores web pages by the stationary distribution of a random surfer. Bellman's (1957) Markov decision process underlies reinforcement learning and decision models in artificial intelligence, and Markov chains are also used for queues, credit-rating transitions and population movement.
FAQ
- What is the Markov property?
- It is the property that the probability of future states depends only on the present state, not on the path taken to reach it; equivalently, given the present, the future is independent of the past.
- Where are Markov chains used?
- They are used in search-engine PageRank, hidden Markov models for speech recognition, MCMC in Bayesian statistics, business-cycle analysis, Markov decision processes in reinforcement learning and many other fields.
Sources reviewed: 2026-10-26
References
- Markov, A. A. (1906). Rasprostranenie zakona bol'shih chisel na velichiny, zavisyaschie drug ot druga. Izvestiya Fiziko-matematicheskogo obschestva pri Kazanskom universitete, 15(2), 135–156.
- Markov, A. A. (1913). An example of statistical investigation of the text Eugene Onegin concerning the connection of samples in chains. Bulletin of the Imperial Academy of Sciences of St. Petersburg, 7(3), 153–162.
- Kolmogorov, A. N. (1936). Zur Theorie der Markoffschen Ketten. Mathematische Annalen, 112, 155–160.
- Shannon, C. E. (1948). A mathematical theory of communication. Bell System Technical Journal, 27(3), 379–423.
- Kemeny, J. G., & Snell, J. L. (1960). Finite Markov Chains. Princeton, NJ: Van Nostrand.
- Bellman, R. (1957). A Markovian decision process. Journal of Mathematics and Mechanics, 6(5), 679–684.
- Baum, L. E., & Petrie, T. (1966). Statistical inference for probabilistic functions of finite state Markov chains. Annals of Mathematical Statistics, 37(6), 1554–1563.
- Rabiner, L. R. (1989). A tutorial on hidden Markov models and selected applications in speech recognition. Proceedings of the IEEE, 77(2), 257–286.
- Hamilton, J. D. (1989). A new approach to the economic analysis of nonstationary time series and the business cycle. Econometrica, 57(2), 357–384.
- Brin, S., & Page, L. (1998). The anatomy of a large-scale hypertextual Web search engine. Computer Networks and ISDN Systems, 30(1–7), 107–117.
- Norris, J. R. (1997). Markov Chains. Cambridge: Cambridge University Press.
- Levin, D. A., Peres, Y., & Wilmer, E. L. (2009). Markov Chains and Mixing Times. Providence, RI: American Mathematical Society.
- Hayes, B. (2013). First links in the Markov chain. American Scientist, 101(2), 92–97.
