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HTTP

\ˌeɪtʃ tiː tiː ˈpiː\abbr.

Filed underWeb DevelopmentSEOInfrastructure

In brief · quick answer

HTTP (HyperText Transfer Protocol) is the application-layer protocol that governs communication between web clients (browsers) and servers.

§ 1 Definition

HTTP is the protocol that powers the web. Every time your browser loads a page, submits a form, or fetches an API response, it uses HTTP. The protocol follows a request-response model: the client sends a request (method, path, headers, optional body) and the server returns a response (status code, headers, body). HTTP is stateless, meaning each request is independent. Servers do not retain memory of previous requests unless techniques like cookies or tokens add session state on top. HTTP is extensible through headers, methods, and status codes. It has evolved through multiple versions: HTTP/2 added multiplexing and header compression, while HTTP/3 replaced TCP with QUIC for lower latency. People often confuse HTTP with HTML, but HTTP moves data of any type: JSON, images, video, and XML.

§ 2 How it works

A client opens a TCP connection (or QUIC stream in HTTP/3) to a server, typically on port 80 for HTTP or port 443 for HTTPS. The client sends an HTTP request with a method (GET, POST, PUT, DELETE, etc.), a target URI, headers (metadata like content type, caching directives, authentication), and an optional body. The server processes the request and returns a response with a status code (200 OK, 404 Not Found, 500 Internal Server Error, etc.), headers, and a body.

§ 3 Why it matters

HTTP affects everything from page load speed to SEO. HTTP headers control caching (which determines how fast your site loads for returning visitors), compression (gzip, Brotli), and security policies (CORS, CSP, HSTS). Misconfigured HTTP headers are a common source of performance and security problems.

§ 4 Common misconception

HTTP is not inherently insecure. Plain HTTP sends data in cleartext, but the protocol itself supports encryption via TLS. The secure variant is HTTPS. There is no excuse for running an unencrypted HTTP site in 2026.

§ 5 Note

HTTP/1.1 allowed persistent connections (keep-alive), which was a major improvement over HTTP/1.0's per-request connection overhead. But it still suffers from head-of-line blocking at the application layer.

§ 6 In code

```http
GET /api/users HTTP/1.1
Host: example.com
Accept: application/json
Authorization: Bearer <token>
```

§ 7 Common questions

Q. What is the difference between HTTP and HTTPS?: A. HTTPS wraps HTTP in TLS encryption, protecting data from eavesdropping and tampering.
Q. What is an HTTP status code?: A. A three-digit code indicating the result of a request. 2xx = success, 3xx = redirection, 4xx = client error, 5xx = server error.

Key takeaways

HTTP is the request-response protocol underlying web communication.
HTTP headers control caching, compression, security, and content negotiation.
Always use HTTPS. Plain HTTP is not acceptable for production.

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Atomic Glue optimizes HTTP configurations for speed and security. From proper caching headers to HTTP/3 support, we ensure your site performs. See our SEO & GEO services.

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# HTTP

HTTP (HyperText Transfer Protocol) is the application-layer protocol that governs communication between web clients (browsers) and servers.

Category: Web Development (also: SEO, Infrastructure)

Author: Atomic Glue Team

## Definition

HTTP is the protocol that powers the web. Every time your browser loads a page, submits a form, or fetches an API response, it uses HTTP. The protocol follows a request-response model: the client sends a request (method, path, headers, optional body) and the server returns a response (status code, headers, body). HTTP is stateless, meaning each request is independent. Servers do not retain memory of previous requests unless techniques like cookies or tokens add session state on top. HTTP is extensible through headers, methods, and status codes. It has evolved through multiple versions: [HTTP/2](/glossary/http2) added multiplexing and header compression, while [HTTP/3](/glossary/http3) replaced TCP with QUIC for lower latency. People often confuse HTTP with HTML, but HTTP moves data of any type: JSON, images, video, and XML.

## How it works

A client opens a TCP connection (or QUIC stream in HTTP/3) to a server, typically on port 80 for HTTP or port 443 for [HTTPS](/glossary/https). The client sends an HTTP request with a method (GET, POST, PUT, DELETE, etc.), a target URI, headers (metadata like content type, caching directives, authentication), and an optional body. The server processes the request and returns a response with a status code (200 OK, 404 Not Found, 500 Internal Server Error, etc.), headers, and a body.

## Why it matters

## Common misconception

HTTP is not inherently insecure. Plain HTTP sends data in cleartext, but the protocol itself supports encryption via TLS. The secure variant is [HTTPS](/glossary/https). There is no excuse for running an unencrypted HTTP site in 2026.

## Note

## In code

## Common questions
Q: What is the difference between HTTP and HTTPS?
A: HTTPS wraps HTTP in TLS encryption, protecting data from eavesdropping and tampering.
Q: What is an HTTP status code?
A: A three-digit code indicating the result of a request. 2xx = success, 3xx = redirection, 4xx = client error, 5xx = server error.

## Key takeaways

HTTP is the request-response protocol underlying web communication.
HTTP headers control caching, compression, security, and content negotiation.
Always use HTTPS. Plain HTTP is not acceptable for production.

## Related entries

Last updated June 2026. Permalink: atomicglue.co/glossary/http