What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
An application program interface (API) is a defined way for one piece of software to request functionality from another. It specifies what a program can access and the rules for making a request, while leaving the provider’s internal implementation behind the interface.
What does API stand for?
API stands for application programming interface. “Application program interface” is also used as a synonym for the same concept in the NIST CSRC glossary.
An API is designed for software-to-software interaction, rather than for a person to operate directly. It exposes defined functions or features that another program can use. The NIST CSRC glossary describes an API as a system access point or library function with well-defined syntax and functionality.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →How does an API work?
An API sets the terms for interaction: what operations are available, what inputs a caller may provide, and what results or responses it can expect. The program using the API follows those rules; the program or system providing it handles the work behind the interface. This makes an API useful to think of as a contract between the provider and the software that calls it. MDN Web Docs uses this contract idea to explain APIs.
#1 Best Overall
A menu or service counter is a helpful analogy: a customer can request an offered service in an accepted way without knowing how it is carried out. The analogy is not literal, though. In software, an API may consist of methods, properties, events, URLs, library functions, or other defined access points—not necessarily a menu or a network request.
Examples of APIs
Browser APIs
A browser API exposes browser capabilities for web applications. For example, the Geolocation API can let a web application request location information. The getUserMedia API can let an application request access to a device’s audio or video. Whether access is available depends on the device and relevant permissions; using an API does not guarantee that access will be granted. These are examples of browser APIs, not requirements that apply to every API. MDN’s API glossary describes these examples.
Rank #2
- Used Book in Good Condition
Library and system interfaces
A program can also call functions exposed by a software library or interact with a system through a defined access point. These interfaces are APIs even when they are not web services. Their syntax and available operations depend on the particular library or system.
Recommended Free Tools
Is an API the same as a web API?
No. An API is the broader term for a defined software interface. A web API is an API used in a web context; it may expose browser capabilities or functionality from a website or service. APIs also include library and system interfaces, so not every API is an internet service.
HTTP, JSON, and a particular architecture may be used by some web APIs, but none of them defines APIs in general. The defining feature is the specified interface and the rules a calling program must follow—not one protocol or data format. For a web-development overview, see MDN’s introduction to client-side APIs.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why do APIs matter?
An API lets a program use functionality without needing to know how the provider implemented it internally. This abstraction can make complex capabilities easier to access: a developer works with the operations and rules the API exposes instead of rebuilding the underlying functionality. The provider can manage its implementation behind the interface, while callers interact with the documented access points. MDN’s web API introduction explains how APIs provide access to browser features.
Quick Recap
Best Value
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
