HTTP is a text based protocol where a client sends a request comprising of a METHOD, an URI and associated meta information represented as MIME-like headers, and possibly a data attachment. The server responds with a status code, a set of headers, and possibly a data attachment. Earlier protocol versions perform a single transaction in a single TCP connection, HTTP/1.1 introduces persistency where a single TCP connection can be reused to perform multiple transactions.

An HTTP method is a single word - usually spelled in capitals - instructing the server to apply a function to the resource specified by the URI. Commonly used HTTP methods are "GET", "POST" and "HEAD". HTTP method names are not restricted in any way, other HTTP based protocols (such as WebDAV) add new methods to the protocol while keeping the general syntax intact.

Headers are part of both the requests and the responses. Each header consists of a name followed by a colon (':') and a field value. These headers are used to specify content-specific and protocol control information.

The response to an HTTP request starts with an HTTP status line informing the client about the result of the operation and an associated message. The result is represented by three decimal digits, the possible values are defined in the HTTP RFCs.