What is Application Program Interface (API)?

API (application program interface) is a set of routines, protocols, and tools for building software applications. The API specifies how software components should interact and APIs are used when programming graphical user interface (GUI) components. A good API makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together.

Types of APIs

There are many different types of APIs for operating systems, applications or websites. Windows, for example, has many API sets that are used by system hardware and applications — when you copy and paste text from one application to another, it is the API that allows that to work.

Most operating environments, such as MS-Windows, provide an API so that programmers can write applications consistent with the operating environment. Today, APIs are also specified by websites. For example, Amazon or eBay APIs allow developers to use the existing retail infrastructure to create specialized web stores. Third-party software developers also use Web APIs to create software solutions for end-users.

Popular API Examples

Programmable Web, a site that tracks more than 13,000 APIs, lists Google Maps, Twitter, YouTube, Flickr and Amazon Product Advertising as some of the the most popular APIs. The following list contains several examples of popular APIs:

1. Google Maps API: Google Maps APIs lets developers embed Google Maps on webpages using a JavaScript or Flash interface. The Google Maps API is designed to work on mobile devices and desktop browsers.

2. YouTube APIs: YouTube API: Google's APIs lets developers integrate YouTube videos and functionality into websites or applications. YouTube APIs include the YouTube Analytics API, YouTube Data API, YouTube Live Streaming API, YouTube Player APIs and others.

3. Flickr API: The Flickr API is used by developers to access the Flick photo sharing community data. The Flickr API consists of a set of callable methods, and some API endpoints.

4. Twitter APIs: Twitter offers two APIs. The REST API allows developers to access core Twitter data and the Search API provides methods for developers to interact with Twitter Search and trends data.

5. Amazon Product Advertising API: Amazon's Product Advertising API gives developers access to Amazon's product selection and discovery functionality to advertise Amazon products to monetize a website.

• answered 8 years ago
• G John

An API is a list of commands as well as the format of those commands that one program can send to another. It is used so that individual programs can communicate with one another directly and use each other's functions.

For instance, Notepad can communicate with the operating system (Windows) by telling it to print a document. It can do this in a number of ways but the most basic form is:

print(document);

This ability is useful in many ways. For one, it allows the Notepad program to be able to print without having to communicate directly with the printer. All the work in communicating, sharing and allocating what gets to print what is done by Windows. All an individual program needs to do is execute the print() command.

This ability is also useful in that Windows can easily change how it deals with different prints or whether it actually prints at all (rather than, say, save to a PDF document) without having to make any changes to Notepad.

API's are provided by any program that allows interaction with other programs. People who write programs but wishes to use the functionality that already exist in other programs can simply look at the API documentation to find the list of commands available to them.

In the context of the web, the API's generally allow you to send commands to programs running on the servers that you connect to from your browser or with the browser itself. This allows you to access resources only available on the server (for instance, logins and passwords).

• answered 8 years ago
• Gul Hafiz