API is an intermediary that allows an application to interact with other operating systems and software. In simple terms, it takes a user response to a system and sends the system’s response back to the user.

For example, when you are on an eCommerce site and you click on ‘add to cart’, the API informs the site that you have added a product to your cart. The website then responds by putting the product in your cart.

With an API, the developer can make a specific request or call to receive specific information. There are four request methods the developer can use with an API:

PUT: used to update data

GET: used to gather information

DELETE: used to delete a post for instance

POST: used to create a new product category for instance

1. Open API

Open API also known as Public API is available to every developer who needs to use it. To use these APIs, you may require an API key or you may need to register. This API aims to make the required data available to the developer.

2. Partner API

This type of API aims to offer access to specific business partners for the aim of generating revenue for both parties involved.

For example, if you wish to integrate an online music streaming service into your app, you can ask for an API. This API will allow easy integration between your app and its service while you provide them with traffic.

3. Private API

Private API helps to improve the internal development of a company. They aren’t available for use by any external user.

In simple terms, an API works by sending a request to another system, seeking to access data or provide a service.

Think of the working of an API as a customer, a bar, the waiter, and the bartender. The customer places their order of cocktails or drinks through the waiter. The waiter then takes this order to the bartender, who gets the drinks and gives them to the waiter. The waiter delivers the made request to the customer and everybody is happy.

In this scenario, the waiter acts as the API. The customer who is the user requests the bartender who is the server through the API. The API takes the request, translates it to easily understandable rules that the bartender easily recognizes and follows. The bartender then creates what was requested and sends it back to the user via the waiter.

There are a lot of ways APIs have proven to be important. Their uses include:

• Connecting devices to the internet
• They serve as a link between everything like automobiles, dishwashers, and also doorbells
• They make it possible to develop and use mobile applications
• They also power desktop applications
• They integrate no-code solutions
• They are the force behind many web applications
• APIs define the data passed between applications, devices, and systems

• Increasing the speed of software and system development: since the use of APIs allow developers to deliver functionality as microservices, it speeds up the process of software development.

This speed is thanks to the elimination of dependencies and the task of code reviews and the rest.

APIs also accelerate systems development by permitting the division of labor. This can be seen in the splitting of tasks when creating the front end and back end of a system.

• Reduce non-performing systems: with APIs, a company can reduce the non-performing systems and the occurrence of outages. Companies use this for example to identify a problem and even get recommendations on fixing it.
• Improve software and system testing: APIs allow the team of engineers to separately test the front ends of a system and its backend. This way, the quality of a test is more thorough.
• Improve security: APIs can be used by an organization to improve its security.
• Enable mobile applications: many mobile applications are powered by APIs. They use this to deliver information to the users.
• Reduce the cost of software development: APIs help in the reduction of development costs by allowing the creation of reusable components. A developer can create a system that serves as a database for information about customers.

With this already set in place, other developers in the organization can use APIs to get this information when needed in cases of customer service, track payments, and also in marketing campaigns.

• Integrate internal and external systems: developers use APIs because they allow easy integration of one system with another.
• Reduce the cost of operations: APIs help to reduce the cost of operation by performing tasks that would have been carried out by humans.

APIs enhance the functionality of both internal and external systems. It also serves to enhance functionality for customers.

Security

The use of APIs in a website can be related to the use of reverse proxies as a layer of security for a website. When a request is sent to a website that uses APIs, your request doesn’t go directly to the server.

Instead, the API delivers your request to the server on your behalf, and then the server sends back the response. By doing this, the chances of your server being attacked would be reduced.

Scalability

With the use of APIs, your website can grow faster. It’s easier to scale your site and it's more flexible when you try to improve your store’s catalog, data, or security.

Speed

APIs allow the user to see what products are available in a store’s inventory, the number that is left, and the price.

Without an API, the customer would have to call the store and ask for the availability of a product and its price and then wait for the response. And so the use of APIs in eCommerce sites makes purchases easier.

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Examples of API Usage

Searching for Hotels

Many travel sites are linked to others so that you can get the best deal on the location you are visiting. So when you provide location details plus the type and number of hotel rooms you would need, the request is sent to the travel sites.

The API takes the request to those sites and gives you the feedback so you can make your pick. So the API acts like a messenger.

Catching The Trend On Social Media

If you need to find out what is happening on social media, the API helps you do this. You can get news on entertainment, sport, or any other category just by navigating to said section.

With the API, you get news relating to your search or the category you have chosen.

Searching for A Profile On Social Media

If you go on Facebook for instance and search for a name, the API informs Facebook’s servers that you need data on that name. Facebook then responds to this by sending everything that matches your search so you can make your choice.

Looking for A Restaurant in A New City

If you are new in a city and feel like eating out, you can easily find your way to a restaurant. Google API will display the hotels around you, and other details like their reviews, business hours, and phone numbers.

Transacting in A Bank

The function of an API can be likened to that of a teller at a bank, where you are the user and the bank is the system.

You place your withdrawal request at the teller, and the teller takes this request to the bank manager. The manager grants your request and provides the teller with what you need. The teller then brings this to you. So the API serves as an intermediary between you and the system.