HTTP

Request-Response Model

HTTP (HyperText Transfer Protocol) is the application-layer protocol that powers the web. Every time a browser fetches a page, it sends an HTTP request to a server specifying a method (GET, POST, PUT, DELETE, etc.), a path, headers with metadata, and optionally a body. The server processes the request and returns an HTTP response containing a status code, response headers, and the requested content. This stateless model — each request is independent — underlies all web communication.

HTTP Versions

HTTP/1.1, standardized in 1997, introduced persistent connections so a single TCPTransmission Control Protocol. A reliable, connection-oriented transport protocol that guarantees ordered, error-checked delivery of data through three-way handshakes, acknowledgments, and retransmission. The foundation of HTTP, SSH, and most internet services. connection can serve multiple requests. HTTP/2 added multiplexing, allowing many requests to share one connection simultaneously, eliminating head-of-line blocking. HTTP/3 replaces TCPTransmission Control Protocol. A reliable, connection-oriented transport protocol that guarantees ordered, error-checked delivery of data through three-way handshakes, acknowledgments, and retransmission. The foundation of HTTP, SSH, and most internet services. with UDPUser Datagram Protocol. A connectionless transport protocol that sends datagrams without establishing a connection or guaranteeing delivery. Faster than TCP, it is preferred for real-time applications like DNS queries, VoIP, gaming, and streaming.-based QUIC, reducing connection setup latency and improving performance on lossy networks. Most modern servers support HTTP/2; HTTP/3 adoption is growing rapidly.

HTTP vs. HTTPS

Plain HTTP transmits all data — including cookies, form inputs, and authentication tokens — without EncryptionThe process of converting plaintext data into ciphertext using a cryptographic algorithm and key, making it unreadable without the corresponding decryption key. The foundation of secure communication on the internet., making it vulnerable to interception and Man-in-the-Middle AttackAn attack where an adversary secretly intercepts and potentially alters communication between two parties who believe they are communicating directly. HTTPS and certificate pinning are primary defenses against this attack. attacks. HTTPSHTTP Secure. The encrypted version of HTTP that uses TLS to protect data in transit between a browser and a web server. Identified by the padlock icon in browsers and the https:// URL scheme. wraps HTTP inside SSL/TLSSecure Sockets Layer / Transport Layer Security. Cryptographic protocols that provide encrypted, authenticated communication over a network. SSL is deprecated; modern implementations use TLS 1.2 or TLS 1.3., providing confidentiality, integrity, and server authentication. Modern browsers mark plain HTTP sites as "Not Secure" and many features (geolocation, service workers, camera access) are restricted to HTTPS origins. Use HTTP Header Analyzer to inspect the security headers a server sends.