What Is API (Application Programming Interface)? – POFTUT

What Is API (Application Programming Interface)?

Application Programming Interface or API is a popular term used in the computing world. API is an interface to access different computing, software, library functions. API defines and creates different access types, functions, parameters, and options to access and use resources or software.

What Is API(Application Programming Interface)?

API exposes different resources like software, library, system, or object to the other entities’ use which is generally a software too. There is no specification for API standard or usage but during years some general rules are accepted.API ensures the interoperability between different computing or software entities too. As software usage is increased today there are a lot of different libraries, systems that provide API. Most of the popular Softwares like operating systems, web services, desktop applications, virtualization software, etc. provide an API.

API Usage and Types

API is provided by different entities with different features, access type, and usage type. Below we have listed some usage examples with the API types.

Library and Framework API

Libraries and frameworks are the most popular use case for the API. In order to use libraries and frameworks API is used by default. API makes is very flexible to use the library and framework because it will separate the user interface from the actual implementation. Implementation is generally very complex where usage with API makes is very easy and straightforward.

Operating System API

Operating systems runs on the computing hardware in order to provide different type of resources to the user-level applications. All of these resources are provided via standardized APIs by the operating systems. For compatibility reasons operating systems provides the APIs with different standards like POSIX, Windows API, etc. POSIX is mainly used for Linux, BSD, and Unix operating systems and distributions and Windows API used by Windows family operating systems.

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Remote APIs

Remote APIs provide access to the remote software, library, or application functions and resources via low-level ways. Remote APIs generally used to call a function, method, or access resource of the remote system. Java Remote Method Invocation is one of the most popular Remote API. Java RMI provides remote access to the Java methods, function, objects via different computers and hosts by using the network.


Web API is used to access remote functions by using HTTP or HTTPS protocols and technologies like JSON, JavaScript, PHP, Python, XML, SOAP, etc. Web APIs are heavily used in order to provide access via networks or the internet. A lot of popular services like Twitter, Google, Facebook, Instagram provides web API to access their services for the 3rd party software or application. Rest is the most popular sub-type of the Web API which heavily uses JSON for communication. Web APIs can be used by different platforms, programming languages than the Web API service.

API Release Policies

APIs provide access to the resources programmatically for everyone by default. But for security, branding reasons access to the APIs should be restricted. The following 3 main policies are used for release and access APIs.

Private API Access is used the APIs created for internal use for the company or application. Only the developer company can access this API.

Partner API Access is restricted and available for specific companies or businesses.Third-party access is available but only for the partners. For example, Uber only provides access to its partners to the Uber API.

Public API Access provides access to everyone to the API. There is no restriction about API access but in some cases, some user authentication may required to use. As an example, Microsoft Windows API is public where every operating system user can access. Also, Twitter API is a public API where the user requires user authentication for the accounts.

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API Documentation

APIs provide access to different resources where every system is very different cases. APIs aim for simple access but, in order to use properly, there is a need for documentation. API documentation is essential to use API properly and lower the time and effort required to use API. The API documentation provides the following information.

  • General Information
  • API Architecture
  • API Functions
  • API Function Examples
  • Use Cases
  • Code Snippets

API documentation can be created in different ways but some programming languages and frameworks provide practical ways for documentation. Python provides the “Pydoc” mechanism where the documentation can be put inside the code. Documents about API can be easily generated from the source code in a clean and structured way. Also, Java programming language provides the “Javadoc” mechanism which is very similar to the “Pydoc”.

API Advantages

API usage provides a lot of advantages.

  • Easy access to the remote resource or function
  • Cross-platform usage of the resources and function
  • Less error and implementation time for resource and function usage
  • Fast resource and function usage
  • More secure usage of the remote resources and functions

Who Creates API?

API is technically created by the developers but from a general point of view different groups can create an API for their software, library, product, or service.

  • Large Tech Companies
  • Service Owners
  • Governments Organizations
  • Software Startups
  • Fan Groups
  • Individuals
  • Software Companies
  • Sport Communities
  • Ecommerce Companies

What Is Provided with API?

API provides easy access to different resources. An API may provide the following resources which vary differently.

  • Login Actions
  • List Of Users
  • List Of Products
  • List Of Tweets
  • Deleting Tweet Action
  • Return Images
  • Provide Song Lyrics
  • Provide Web Page Parts or Contents
  • Provide Latest Current Exchange Rates
  • Start A Virtual Machine On The Cloud
  • Make A Payment
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API Technologies

In order to create an API, there is some need for helper technologies. These API technologies make API creation and usage more fast and reliable.

JSON is one of the most popular API technology and data exchange format. JSON is used to exchange data in an easy to read and parse format. Also, the JSON format is supported by all popular programming languages and frameworks.

SOAP is another popular data exchange format that is more complex than JSON. SOAP is mainly used for enterprise-level applications do define the structure of data format and exchange.

REST is a web-based technology where the data is transferred by using HTTP/HTTPS protocols without any restriction and block.

Popular APIs

Today IT mainly relies on using API. Even making web search Google uses different APIs to accomplish searches. Below we will list some of the popular APIs.

Google Maps API provides access to the Google Map resources like maps, locations, businesses, and embeds this information into the other applications easily.

YouTube API provides an integrated YouTube platform with different applications and web sites which provide information like Analytics, Data, Live Streaming, Player services.

Flickr API provides access to the Flickr photo library and easily embed different applications.

Twitter API can be used to access Twitter resources like Tweets, Login, Create/Delete/Retweet Tweets. Also, a search can be done on all tweets according to the different terms like the hashtag, date, user, location, etc by using Twitter API.

Microsoft Windows API provides operating system resources and functions to the Windows desktop applications. For example, In order to create a window for the application, the Windows API is used.

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