Any device, tool or technique that is used to help ensure the characteristics of information are maintained through any of the information states.
Almost all programming languages in wide use today are “stateful,” meaning that the system is keeping track of events using system “states.” What’s a state? In programming, variables and objects hold values. These values belonging to variables and objects are, at any given point in time, the states.
If x = 3, and then x = 6, then x had two states, each with its own value.
Modern computers can keep track of millions of these states at any given time.
Most computer languages in use today are object-oriented languages, which are, by nature, stateful. Some computer scientists believe, however, that the future is in functional programming, which is stateless. Learn about the difference in this video.