What Is API & Various API Methods? A Guide

When you check the weather on your phone or see a Google Map embedded within a real estate website, you are witnessing Application Programming Interfaces (APIs) at work. An API is a set of rules that permits different software programs to interact with one another. Understanding API methods is central to this interaction. They serve as the action words in the language of APIs, telling a system what operation to perform. These methods are the primary tools used for making modern, interconnected software.

APIs operate as intermediaries, translating requests from a client (such as your web browser) into actions on a server. This process lets applications share data and functionality. For any developer, mastering API interaction is vital for producing efficient and scalable applications. This text will provide a detailed examination of HTTP API methods and their purpose in development.

What Are API Methods?

An API method specifies the action a client wants to perform on a resource. When you make an API call, the method dictates whether you want to read, create, update, or delete data. These methods are the core commands you issue to an API.

These methods map directly to common data operations. For instance, retrieving a user's profile uses a different method than updating their email address. This clear separation of actions makes APIs predictable and easy to use. The relationship is direct: an API method corresponds to a specific HTTP request type.

Common Terminology

To work with APIs, we must understand some common terms.

• Endpoint: An endpoint is the specific URL where an API can be accessed. For example, /users/123 could be an endpoint to interact with a specific user.

• Request Body: The request body contains data you send to the server. It is primarily used with POST, PUT, and PATCH methods.

• Payload: The payload is the data contained within the request body. It's often formatted in JSON.

• Headers: Headers provide metadata about the request, such as authentication tokens or the content type of the payload.

• Authentication: This is the process of verifying the identity of the client making the request. It ensures that only authorized users can access the API.

• Response Status: A response status is a three-digit code returned by the server. It indicates whether the request was successful, failed, or requires further action.

What are HTTP Requests and API Methods?

HTTP (HyperText Transfer Protocol) is the foundation of data communication on the web. According to the Mozilla Developer Network (MDN), an authority on web standards, HTTP provides a standard way for clients and servers to communicate. API communication relies on this same protocol.

HTTP requests are structured messages sent from a client to a server. Each request includes a method, the endpoint URL, headers, and sometimes a body containing a payload. This structure ensures the server understands exactly what the client wants.

The Different API Methods in HTTP Requests

The core of API interaction lies in a set of standard HTTP verbs. These are the primary api methods you will use daily.

• GET: Used to retrieve data from a server.

• POST: Used to submit new data to the server.

• PUT: Used to update an existing resource completely.

• DELETE: Used to remove a resource.

• PATCH: Used to apply partial modifications to a resource.

Parameters, Headers, and Authentication in HTTP Requests

Imagine you open a food delivery app like Zomato to find an open Italian restaurant nearby. The action of searching triggers an HTTP request from your phone to Zomato's servers. Here is what happens behind the scenes.

1. Authentication: Proving It's You

Before your search is even sent, the app must prove to the server that you are a valid, logged-in user. When you first signed in, the app received a unique, secret token.

• How it works: With every request you make, like searching for food, the app attaches this authentication token inside an Authorization header. This acts like a digital ID card, telling the server, "This is a legitimate request from a verified user." This step is crucial for securing your account and personal data.

2. Parameters: Specifying Your Search

You don't want every restaurant in the city; you want Italian food that's open now. You apply these filters in the app, and they become query parameters in the request URL.

• How it works: The request is sent to an endpoint like api.zomato.com/restaurants. To filter the results, the app adds your choices to the end of the URL. The final URL might look like this: .../restaurants?cuisine=italian&status=open
Here, cuisine=italian and status=open are parameters that tell the server to only return restaurants matching those exact criteria. It is important that sensitive information, such as passwords or payment details, is never sent this way in a URL. That data is sent securely in the request's body, not as a visible parameter.

3. Headers: Providing Technical Context

The headers are the technical instructions for the server. They are sent along with your authentication token and the main request.

• How it works: One common header is Content-Type. If you were submitting data (like a review), this header would tell the server what kind of data it is, for example, application/json. Think of headers as the "shipping label" on a package that tells the recipient how to handle the contents.

4. Response Status: The Server's Reply

After Zomato's server receives and processes your authenticated and filtered request, it sends a response status code back to your app. This code tells the app the outcome of the request.

• Possible Outcomes:

  • 200 OK: Success! The server found Italian restaurants and sends the list back to be displayed on your screen.

  • 404 Not Found: The server understood your request, but no restaurants matched your specific filters (no open Italian places were found).

  • 500 Internal Server Error: Something went wrong on Zomato's end. The app might show you a generic error message like, "We're having trouble, please try again later."

In-Depth Look at API Methods

Here, we will analyze each of the primary HTTP methods in detail.

1) GET Method

The GET method is used exclusively to retrieve resources. It is a read-only operation and should never change the state of the server.

You use GET requests to fetch data, like a user's details or a list of products. The server processes the request and returns the requested data in the response body.

Example: Fetching user data

HTTP

• Response Status for GET: A successful GET request returns a 200 OK status with the data. If the resource does not exist, it returns a 404 Not Found.

• Common Headers: Authorization for protected routes and Accept to specify the desired response format.

2) POST Method

The POST method is used to create a new resource on the server. Think of it as submitting a new entry to a database.

When you create a new user or publish a blog post, you send a POST request. The data for the new resource is contained in the request body, typically as a JSON payload.

Example: Creating a new user

HTTP

• Response Status for POST: A successful creation usually returns a 201 Created status. If the request is malformed, you might receive a 400 Bad Request.

• Significance of Request Body: The request body and its payload are essential. They carry the information needed to construct the new resource.

3) PUT Method

The PUT method updates an existing resource completely. It replaces the entire target resource with the data provided in the request payload.

Use PUT when you need to overwrite all information for an existing user. If you only send one field, PUT will often delete the others.

Example: Updating user information

HTTP

• Response Status for PUT: A successful update returns 200 OK or 204 No Content if the response has no body.

• Idempotency: PUT is idempotent. This means making the same PUT request multiple times has the same effect as making it once. POST is not idempotent; multiple POST requests will create multiple new resources.

4) DELETE Method

The DELETE method removes a specified resource. It is a straightforward and permanent action.

You use DELETE to remove a user, a post, or any other resource. The resource to be deleted is identified by the endpoint URL.

Example: Deleting a user

HTTP

• Response Status for DELETE: A successful deletion typically returns 200 OK or 204 No Content.

• Resource Identification: It is critical to ensure the endpoint URL correctly identifies the resource. An incorrect URL could lead to accidental deletion of the wrong data.

5) PATCH Method

The PATCH method applies a partial update to a resource. Unlike PUT, it only modifies the fields included in the payload.

Use PATCH when you want to change a single piece of information, like a user's email address, without affecting their other data.

Example: Updating a user's email

HTTP

• Response Status for PATCH: A successful patch returns 200 OK or 204 No Content.

• PATCH vs. PUT: PATCH is for partial updates, while PUT is for complete replacement. This makes PATCH more efficient for minor changes.

What Is RESTful API Design?

REST (Representational State Transfer) is an architectural style for designing networked applications. It relies on a stateless, client-server communication model where HTTP methods are used to perform operations on resources.

The key principles of REST involve using standard HTTP api methods, having predictable resource URLs, and being stateless. The Internet Engineering Task Force (IETF) defines these standards in documents like RFC 9110, ensuring interoperability. REST APIs use these methods to perform CRUD (Create, Read, Update, Delete) operations.

The Relationship Between RESTful Design and API Methods

RESTful design provides a logical framework for using HTTP api methods. Each method has a clear purpose that aligns directly with CRUD operations.

In a RESTful API, endpoints are designed as nouns (e.g., /users), and the methods are verbs that act on those nouns. For example, a GET request to /users retrieves a list of users, while a POST request to the same endpoint creates a new user.

Advanced Concepts and Best Practices for API Methods

Optimizing API Performance with Method Usage

Choosing the right method impacts performance. For instance, using GET for data retrieval allows for caching, which significantly speeds up response times for repeated requests.

We recommend designing clear and predictable endpoints. For large datasets, you should integrate pagination and filtering into your GET requests using query parameters (e.g., /posts?page=2&limit=20). This prevents sending massive payloads and improves efficiency.

Handling Errors and Response Status Codes

Proper error handling is essential for a production-ready API. You must use standard HTTP status codes to indicate the outcome of a request.

Studies show that developers value clear error messages. For example, a 400 Bad Request should be accompanied by a response body explaining what was wrong with the request. According to the 2024 State of the API Report by Postman, API reliability and clear documentation are top priorities for development teams.

Example of a detailed error response:

JSON

Security in API Methods

Protecting your API requires strong authentication to verify user identity and authorization to define their permissions. Standard protocols like OAuth 2.0 and token-based systems like JSON Web Tokens (JWT) are effective for securing endpoints.

All API communication must be encrypted using HTTPS to guard against data interception. Sensitive information, such as passwords or personal data, should only be sent within the request body of a POST, PUT, or PATCH method, never as URL parameters.

To defend against injection attacks, it is vital to validate and sanitize all user-supplied input. This is a primary defense against Cross-Site Scripting (XSS), where malicious scripts are injected into web pages viewed by other users. Always encode output before rendering it in a browser.

Control which domains can access your API from a browser by correctly configuring Cross-Origin Resource Sharing (CORS) headers. A strict CORS policy allows only trusted web applications to make requests, mitigating certain types of attacks. Combining these security measures is fundamental to a secure API architecture.

Conclusion

Understanding and correctly implementing api methods is non-negotiable for building efficient, scalable, and secure applications. These methods—GET, POST, PUT, DELETE, and PATCH—are the building blocks of API communication, enabling your applications to integrate and synchronize data seamlessly.

By adhering to RESTful principles and security best practices, you empower your team to build production-ready systems that are both powerful and reliable. As technology advances, the fundamental importance of well-structured api methods will remain a cornerstone of software development.

FAQs

1) What are the 5 methods of API? 

The five main HTTP methods used in APIs are GET (retrieve), POST (create), PUT (update/replace), DELETE (remove), and PATCH (partially update). Each performs a distinct action on a server resource.

2) What is an API method? 

An API method is a command included in an API request that tells the server what action to perform. It defines the interaction, such as retrieving data with GET or creating new data with POST.

3) What are REST API methods? 

REST API methods are the standard HTTP methods used within the REST architectural style. These include GET, POST, PUT, DELETE, and PATCH, which correspond to the four basic CRUD (Create, Read, Update, Delete) operations.

4) What are the 5 methods of HTTP? 

The five main HTTP methods discussed are GET, POST, PUT, DELETE, and PATCH. These verbs define the type of request being made to a server and are fundamental to how APIs and the web function.

5) What’s the difference between PUT and PATCH?

PUT replaces an entire resource with new data, while PATCH applies partial modifications to a resource, updating only the specified fields.