# Getting Started with cURL

## 1\. What is cURL

### Problem

When we open a website in a browser, we only see the final output.  
But we do not understand how the request is sent in the background, which headers are going, and how the response is coming.  
And it is also not clear how to talk to a server without using a browser.

### Explanation

cURL is a command-line tool that is used to send requests to a server and receive responses.  
In simple words, cURL is like a messenger that talks directly to the server on your behalf.

### Example

You type in the terminal:  
`curl` [`google.com`](http://google.com)

And you get the raw response from the server.

### Summary

cURL is a tool that sends requests and gets responses.

## 2\. Why programmers need cURL

### Problem

Developers need to test whether the server is working properly or not, even without using a browser.

### Explanation

Programmers use cURL to:

* test APIs
    
* debug servers
    
* check headers and status codes
    

### Example

Before building the frontend, if you want to check the backend, you can test it directly using cURL.

### Summary

cURL is a developer’s testing tool.

## 3\. Making your first request using cURL

### Step 1: Check if cURL is installed

Type in terminal / CMD:  
`curl --version`

If the version is shown → you are ready.

### Step 2: Basic GET request

Example:  
`curl` [`https://www.google.com`](https://www.google.com)

This will return Google’s HTML response.

### Step 3: Calling an API (real use)

`curl` [`https://jsonplaceholder.typicode.com/posts/1`](https://jsonplaceholder.typicode.com/posts/1)

Response:  
`{ "userId": 1, "id": 1, "title": "...", "body": "..." }`

This means we fetched data from the server.

### Step 4: POST request (sending data)

`curl -X POST` [`https://jsonplaceholder.typicode.com/posts`](https://jsonplaceholder.typicode.com/posts)`   -H "Content-Type: application/json"   -d '{"title":"Hello","body":"First post","userId":1}'`  
Meaning:

* `-X POST` → method
    
* `-H` → header
    
* `-d` → data (body)
    
    ###   
    Step 5: Request with authentication
    
    `curl` [`https://api.example.com/profile`](https://api.example.com/profile)`   -H "Authorization: Bearer YOUR_TOKEN"`
    
    ##   
    5\. Using cURL to talk to APIs
    
    ### Problem
    
    Testing APIs in a browser is a bit limited.
    
    ### Explanation
    
    Using cURL, we can directly call APIs:
    
    * GET requests
        
    * POST requests
        
    * send headers with data
        
    
    ### Example
    
    `curl` [`https://api.github.com/users/octocat`](https://api.github.com/users/octocat)
    
    This returns JSON data.
    
    ### Summary
    
    cURL = API calling tool.
    
    ---
    
    # 6\. Common mistakes beginners make with cURL
    
    ### Problem
    
    Beginners get errors and do not understand where the mistake is.
    
    ### Explanation
    
    Common mistakes:
    
    * forgetting http/https
        
    * wrong URL
        
    * internet is off
        
    * wrong quotes or spaces
        
    
    ### Example
    
    `curl` [`google.com`](http://google.com) (may not always work)  
    `curl` [`https://google.com`](https://google.com) (correct)
    
    ### Summary
    
    Most errors happen because of small typing mistakes.