Instance (computer science)

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In computer science, an instance or token (from metalogic and metamathematics) is an occurrence of a software element that is based on a type definition. ^[1]: 1.3.2 When created, an occurrence is said to have been instantiated, and both the creation process and the result of creation are called instantiation.

Class instance

An object-oriented programming (OOP) object created from a class. Each instance of a class shares a data layout but has its own memory allocation.

Procedural instance

Although isn't common the use of this concept in computer science each procedure call also was considered an "instance" of the procedure in Simula. ^[1]: 1.3.2

Computer instance

An occurrence of a virtual machine which typically includes storage, a virtual CPU.

Polygonal model

In computer graphics, it can be instantiated in order to be drawn several times in different locations in a scene which can improve the performance of rendering since a portion of the work needed to display each instance is reused.

Program instance

In a POSIX-oriented operating system, it refers to an executing process. It is instantiated for a program via system calls such as fork() and exec(). Each executing process is an instance of a program which it has been instantiated from.^[2]