🌐 1️⃣ HTTP & HTTPS
🔸 What is HTTP?
HTTP (HyperText Transfer Protocol) is the foundation of communication on the web.
It defines how data is requested and delivered between a client (like Postman or browser) and a server.
When you type a URL or send an API request:
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The client sends an HTTP request.
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The server processes it and returns a response (data, status code, headers).
🧩 Example:
🔸 What is HTTPS?
HTTPS (HTTP Secure) is the secure version of HTTP, where communication between client and server is encrypted using SSL/TLS.
This ensures:
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🔒 Data privacy (cannot be intercepted easily)
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✅ Authentication (verifies server identity)
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🛡️ Integrity (data not altered in transit)
💡 In short:
HTTP = plain communication
HTTPS = secure & encrypted communication
📦 2️⃣ Resource & Payload
🔹 Resource
In an API, everything is treated as a resource — users, posts, products, or orders.
Each resource is identified by a unique URL (endpoint).
🧠 Example:
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/users→ represents a collection of users -
/users/5→ represents a single user with ID = 5
So when you make a request:
You’re requesting the resource “User 5.”
🔹 Payload
The payload is the data sent to the server in the body of an HTTP request — usually with POST or PUT methods.
🧾 Example (POST request payload):
Here, this JSON object is the payload that the API receives and processes.
Tip:
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GET requests don’t usually have payloads.
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POST/PUT requests do.
🧮 3️⃣ HTTP Methods
HTTP methods define what action you want to perform on a resource.
Here are the most common methods used in API testing 👇
| Method | Description | Example |
|---|---|---|
| GET | Retrieve data from a server | GET /users |
| POST | Send new data to the server (create resource) | POST /users |
| PUT | Update an existing resource | PUT /users/3 |
| PATCH | Partially update a resource | PATCH /users/3 |
| DELETE | Remove a resource | DELETE /users/3 |
| HEAD | Same as GET but without body (for metadata) | HEAD /users |
💬 Real-life analogy:
| Action | Example | HTTP Method |
|---|---|---|
| View list of customers | “Show me all users” | GET |
| Add new customer | “Register a new user” | POST |
| Update user details | “Change email of user 3” | PUT/PATCH |
| Remove user | “Delete user 3” | DELETE |
Sample HTTP post request:
🔗 4️⃣ URI, URL, URN, and Endpoint
These four terms often confuse beginners, so let’s simplify them 👇
🧱 URI (Uniform Resource Identifier)
A URI is a general term for identifying a resource — it can be a name, location, or both.
It’s the umbrella term that covers both URL and URN.
🌍 URL (Uniform Resource Locator)
A URL tells you where a resource is located on the web.
It includes the protocol, domain, and path.
🧾 Example:
Here:
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https→ Protocol -
api.github.com→ Domain -
/users/hitendra→ Path to the resource
So this URL locates the user resource named “hitendra” in GitHub’s API.
🧾 URN (Uniform Resource Name)
A URN identifies a resource by name, not by its location.
It doesn’t include protocol or domain.
Example:
This refers to a book by its ISBN number — not where it is stored.
📍 Endpoint
An Endpoint is the specific URL where an API resource can be accessed.
It’s the address you hit when making API calls.
Example:
📊 Visual Summary Diagram
[Client] → [HTTP/HTTPS Request] → [Server]
↘ Resource (e.g., /users/5)
↘ Payload (if POST/PUT)
↘ Endpoint = Base URL + Resource Path
URI, URL, URN, Endpoint
🧠 Quick Recap
✅ HTTP – defines communication protocol
✅ HTTPS – secure version of HTTP
✅ Resource – entity (user, post, etc.)
✅ Payload – data sent to server
✅ HTTP Methods – actions on resources
✅ URI = identifier
✅ URL = locator
✅ URN = name
✅ Endpoint = actual callable address
