Mastering Flask Web Development - Second Edition

HTTP

The Hypertext Transfer Protocol (HTTP) is a request–response protocol that belongs to layer 7 (the application layer). This layer interacts with the application itself. Some other protocols that belong to layer 7 are the Simple Mail Transfer protocol (SMTP), Network File System (NFS), and the File Transfer Protocol (FTP), to name a few.

HTTP was designed to be used by clients (user agents) to request resources from a server. These resources can be HTML files or any other content, such as JSON, XML, or media files. These requests for resources are identified by the network using unified resource locators (URLs).

A URL is a specific type of URI, composed of the following elements:

<scheme>://<authority>/<path>/<query><fragment>

The preceding ...