Hypertext Transfer Protocol (HTTP) é um protocolo da camada de aplicação para a transmissão de documentos de hipermídia, tal com HTML. Ele foi projetado para a comunicação entre navegadores web e servidores web, mas ele também pode ser usado para outros propósitos. HTTP segue o clássico Modelo cliente-servidor, com um cliente abrindo uma conexão para fazer uma requisição, e então esperando até que ele receba uma resposta. HTTP é um protocolo sem estado, significando que o servidor não manterá qualquer dado (estado) entre duas requisições. Apesar de frequentemente ser baseado na camada TCP/IP, ele pode ser utilizado em qualquer camada de transporte confiável;  isto é, um protocolo que não perda menssagens silenciosamente tal como UDP.

Learn how to use HTTP with guides and tutorials.

Overview of HTTP
The basic features of the client-server protocol: what it can do and its intended uses.
HTTP Cache
Caching is very important for fast Web sites. This article describes different methods of caching and how to use HTTP Headers to control them.
HTTP Cookies
How cookies work is defined by RFC 6265. When serving an HTTP request, a server can send a Set-Cookie HTTP header with the response. The client then returns the cookie's value with every request to the same server in the form of a Cookie request header. The cookie can also be set to expire on a certain date, or restricted to a specific domain and path.
HTTP Access Control (CORS)
Cross-site HTTP requests are HTTP requests for resources from a different domain than the domain of the resource making the request. For instance, an HTML page from Domain A (http://domaina.example/) makes a request for an image on Domain B ( via the img element. Web pages today very commonly load cross-site resources, including CSS stylesheets, images, scripts, and other resources. CORS allows web developers to control how their site reacts to cross-site requests.
Evolution of HTTP
A brief description of the changes between the early versions of HTTP, to the modern HTTP/2 and beyond.
Mozilla web security guidelines
A collection of tips to help operational teams with creating secure web applications.
HTTP Messages
Describes the type and structure of the different kind of messages of HTTP/1.x and HTTP/2.
A typical HTTP session
Shows and explains the flow of a usual HTTP session.
Connection management in HTTP/1.x
Describes the three connection management models available in HTTP/1.x, their strengths, and their weaknesses.


Browse through detailed HTTP reference documentation.

HTTP Headers
HTTP message headers are used to describe a resource, or the behavior of the server or the client. Custom proprietary headers can be added using the X- prefix; others in an IANA registry, whose original content was defined in RFC 4229. IANA also maintains a registry of proposed new HTTP message headers.
HTTP Request Methods
The different operations that can be done with HTTP: GET (en-US), POST (en-US), and also less common requests like OPTIONS (en-US), DELETE (en-US), or TRACE (en-US).
HTTP Status Response Codes
HTTP response codes indicate whether a specific HTTP request has been successfully completed. Responses are grouped in five classes: informational responses, successful responses, redirections, client errors, and servers errors.
CSP directives
The Content-Security-Policy (en-US) response header fields allows web site administrators to control resources the user agent is allowed to load for a given page. With a few exceptions, policies mostly involve specifying server origins and script endpoints.

Tools & resources

Helpful tools and resources for understanding and debugging HTTP.

Firefox Developer Tools
Network monitor
Mozilla Observatory

A project designed to help developers, system administrators, and security professionals configure their sites safely and securely.

Tools to check your cache-related headers
How Browsers Work
A very comprehensive article on browser internals and request flow through HTTP protocol. A MUST-READ for any web developer.