In computer science and automata theory, a state is a unique configuration of information in a program or machine. Computer science (or computing science) is the study and the Science of the theoretical foundations of Information and Computation and their It is a concept that occasionally extends into some forms of systems programming such as lexers and parsers. Systems programming (or system programming) is the activity of Programming System software. In Computer science, lexical analysis is the process of converting a sequence of characters into a sequence of tokens In Computer science and Linguistics, parsing, or more formally syntactic analysis, is the process of analyzing a sequence of tokens to

Whether the automaton in question is a finite state machine, a pushdown automaton or a full-fledged Turing machine, a state is a particular set of instructions which will be executed in response to the machine's input. In Automata theory, a pushdown automaton (PDA is a finite automaton that can make use of a stack containing data Turing machines are basic abstract symbol-manipulating devices which despite their simplicity can be adapted to simulate the logic of any Computer Algorithm The state can be thought of as analogous to a practical computer's main memory. The behavior of the system is a function of (a) the definition of the automaton, (b) the input and (c) the current state.

• Compatible states - are states in a state machine which do not conflict for any input values. Thus for every input, both states must have the same output, and both states must have the same successor (or unspecified successors) or both must not change. Compatible states are redundant if occurring in the same state machine.
• Equivalent states are states in a state machine which, for every possible input sequence, the same output sequence will be produced - no matter which state is the initial state.
• Distinguishable states are states in a state machine which have at least one input sequence which causes different output sequences - no matter which state is the initial state.

In information processing, a state is the complete set of properties (for example, its energy level, etc. Information processing is the change (processing of Information in any manner detectable by an observer. A quantum mechanical system or particle that is bound, confined spacially can only take on certain discrete values of energy as opposed to classical particles which see state (physics)) transmitted by an object to an observer via one or more channels. In Control theory, a state observer is a system that models a real system in order to provide an estimate of its internal state, given measurements of the Input Channel, in communications (sometimes called communications channel) refers to the medium used to convey Information from a Any change in the nature or quantity of such properties in a state is detected by an observer and thus a transmission of information occurs. Information as a concept has a diversity of meanings from everyday usage to technical settings

An information system or protocol that relies upon state is said to be stateful. The term information system (IS sometimes refers to a System of persons Data records and activities that process the data and Information in an organization In computing, a protocol is a convention or standard that controls or enables the connection Communication, and Data transfer between two computing One that does not is said to be stateless. For example, there are stateless firewalls and stateless servers, and HTTP is considered a stateless protocol. In Computing, a stateful firewall (any firewall that performs stateful packet inspection ( SPI) or stateful inspection) is a firewall A stateless server is a server that treats each Request as an independent Transaction that is unrelated to any previous request Hypertext Transfer Protocol ( HTTP) is a Communications protocol for the transfer of information on the Internet. A character encoding such as ISO 2022 is said to be stateful if the interpretation of a particular code value depends on the code values that came before it. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page ISO 2022, more formally ISO/IEC 2022 "Information Technologyâ€”Character code structure and extension techniques" is an ISO standard (equivalent to the