Editing Application binary interface (section)

{{short description|Interface to software defined in terms of in-process, machine code access}}
{{Use dmy dates|date=June 2020}}
[[File:Linux kernel interfaces.svg|thumb|300px|A high-level comparison of in-kernel and kernel-to-userspace APIs and ABIs]]
[[File:Linux API and Linux ABI.svg|thumb|300px|The [[Linux kernel]] and [[GNU C Library]] define the [[Linux kernel interfaces#Kernel–user space API|Linux API]]. After compilation, the binaries offer an ABI. Keeping this ABI stable over a long time is important for [[Independent software vendor|ISVs]].]]

An '''application binary interface''' ('''ABI''') is an [[interface (computing)|interface]] exposed by [[software]] that is defined for in-[[Process (computing)|process]] [[machine code]] access. Often, the exposing software is a [[Library (computing)|library]], and the consumer is a [[computer program|program]].

An ABI is at a relatively low-level of [[abstraction (computer science)|abstraction]]. Interface compatibility depends on the target [[computer hardware|hardware]] and the [[software build]] [[toolchain]]. In contrast, an [[application programming interface]] (API) defines access in [[source code]] which is a relatively high-level, hardware-independent, and [[human-readable]] format. An API defines interface at the source code level, before compilation, whereas an ABI defines an interface to compiled code.

API compatibility is generally the concern for [[system design]] and of the toolchain. However, a [[programmer]] may have to deal with an ABI directly when writing a program in a multiple [[programming language|languages]] or [[compiler]]s.

A complete ABI enables a program that supports an ABI to run without modification on multiple operating systems that provide the ABI. The target system must provide any required libraries (that implement the ABI), and there may be other prerequisites.