sisend

Sisend is the Estonian term for input, used in information technology and computing to denote data provided to a computer, program, or system for processing. It contrasts with väljund, which means output. In computing, inputs originate from various sources: user actions via keyboards, mice, and touchscreens; sensors in devices; files and data streams; network communications; or configuration settings. Programs read sisend through input interfaces such as keyboards, command lines, sockets, file readers, or APIs. Input data are often validated and transformed into a suitable internal representation before processing, a step known as input validation. The concept of input is central to algorithms, data processing, and user interfaces; it defines how a system receives information and how the system should respond.

Common topics include input formats (data structure and encoding), input validation, default values, and error handling. In programming, the term appears in phrases like input handling, input stream, and input devices. In Estonian computing terminology, forms such as sisendi voog (input stream), sisendallikas (input source), and sisendi parameeter (input parameter) are used.

Examples illustrate the range of sisend: a calculator receives numeric input from a keyboard; a weather sensor provides continuous environmental data as sensor input; a web form submits user data as HTTP input.

The term is widely understood in Estonian IT literature and education and applies to both interactive and batch processing contexts.