What is HTTP?

Table of Contents 4 sections

What is HTTP?

HTTP, or Hypertext Transfer Protocol, is the application-layer protocol that forms the foundation of data communication on the World Wide Web. Originally developed by Tim Berners-Lee at CERN in 1989, HTTP defines how messages are formatted and transmitted between web browsers (clients) and web servers. When you type a URL into your browser, an HTTP request is sent to the server, which processes it and returns an HTTP response containing the requested resource.

HTTP is a stateless protocol, meaning each request-response cycle is independent and the server retains no memory of previous interactions. This stateless design simplifies server implementation and improves scalability, though it requires mechanisms like cookies and sessions to maintain user state across multiple requests in modern web applications.

HTTP Methods and Status Codes

HTTP defines several request methods that indicate the desired action to be performed on a resource. The most common methods are GET (retrieve a resource), POST (submit data), PUT (update a resource), DELETE (remove a resource), and PATCH (partially modify a resource). These methods form the basis of RESTful API design and are fundamental to how web applications communicate.

HTTP responses include status codes that indicate the outcome of a request. Codes in the 200 range indicate success, 300 range indicate redirection, 400 range indicate client errors (such as the well-known 404 Not Found), and 500 range indicate server errors. Understanding these codes is essential for debugging web applications and configuring security rules in firewalls and WAFs.

HTTP vs HTTPS

Standard HTTP transmits data in plaintext, making it vulnerable to eavesdropping, man-in-the-middle attacks, and data tampering. HTTPS (HTTP Secure) addresses these vulnerabilities by encrypting the communication between client and server using TLS (Transport Layer Security). When a browser connects to an HTTPS site, a TLS handshake establishes an encrypted tunnel before any HTTP data is exchanged.

HTTPS has become the de facto standard for all web traffic. Search engines penalise HTTP-only sites in rankings, browsers display security warnings for unencrypted connections, and modern web features like service workers and HTTP/2 require HTTPS. For WordPress sites, migrating to HTTPS is one of the most impactful security improvements an administrator can make.

HTTP Security Considerations

Even with HTTPS, HTTP traffic can be exploited if the application is not properly secured. Attackers target HTTP headers, cookies, and request parameters to carry out cross-site scripting (XSS), cross-site request forgery (CSRF), and injection attacks. Security headers such as Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security provide additional layers of defence by instructing browsers on how to handle content securely.

Web Application Firewalls inspect HTTP traffic for malicious payloads and enforce policies at the application layer. Properly configuring HTTP security headers, enforcing HTTPS, and deploying a WAF are all critical steps in protecting any web application from HTTP-based threats.