What is "automata"

An automaton is supposed to run over a given sequence of inputs in discrete time steps. For each step, an automaton receives an input that is obtained from a set of symbols or letters, which is called the alphabet. At any time, the symbols that serve as input for the automaton form a finite sequence of symbols, which is called a word. An automaton contains a finite set of states. For each instant of time during execution, the automaton is in one of its states. In short, an automaton is a mathematical object that has an input word and decides whether to accept or reject this word. Since all computational problems are reducible to the word acceptance problem (all instances of the problem can be represented by a finite size of symbols), automata theory plays an important role in computational theory.