In component-based programming (

Visual Basic Visual Basic is a name for a family of programming languages from Microsoft. It may refer to: * Visual Basic (.NET), the current version of Visual Basic launched in 2002 which runs on .NET * Visual Basic (classic), the original Visual Basic suppo ...

.NET The .NET platform (pronounced as "''dot net"'') is a free and open-source, managed code, managed computer software framework for Microsoft Windows, Windows, Linux, and macOS operating systems. The project is mainly developed by Microsoft emplo ...

WinForms, Gambas,

Delphi Delphi (; ), in legend previously called Pytho (Πυθώ), was an ancient sacred precinct and the seat of Pythia, the major oracle who was consulted about important decisions throughout the ancient Classical antiquity, classical world. The A ...

, Lazarus etc.), a form is a representation of a GUI window. A form contains components and controls, typically including "OK" and "Cancel" buttons; these objects provide a high-level abstraction of standard or custom widgets which are typically much easier to manipulate than the GUI's underlying API. At design time, visual controls (buttons, text boxes, and the like) and non-visual components (timers,

database connection A database connection is a facility in computer science that allows client software to talk to database server software, whether on the same machine or not. A connection is required to send commands and receive answers, usually in the form of a ...

s, layout aids, and so on) are placed on the form. These controls and components are positioned and sized interactively, and their properties and

event handler In computing, an event is a detectable occurrence or change in the system's state, such as user input, hardware interrupts, system notifications, or changes in data or conditions, that the system is designed to monitor. Events trigger responses or ...

s are set with a special editor typically laid out as a grid. At runtime, automatically generated code creates instances of these controls and components, and sets their properties. Historically, forms were often implemented as screens on a

block-oriented terminal A computer terminal is an electronic or electromechanical computer hardware, hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to ...

connected to a mainframe computer. HTML forms are conceptually very similar.

See also