HTTP requests and responses are typically sent over the internet using the Transmission Control Protocol (TCP) as the underlying protocol. When a client (e.g. a web browser) makes an HTTP request, it establishes a TCP connection with the server hosting the requested resource. Once the connection is established, the request is sent over the TCP connection as a stream of bytes, usually in the form of text, that include the request method, headers, and possibly a body.
The server then receives the request, parses it, and generates a response. The response is then sent back to the client over the same TCP connection, also as a stream of bytes that include the response status code, headers, and possibly a body. Once the response has been received, the connection can be closed or kept open for subsequent requests.
To facilitate the sending and receiving of HTTP requests and responses, various libraries, protocols, and tools are used, such as cURL, Postman, Node.js, and many others.
