Lesson 2: The request envelope: method, address, and headers

Lesson objectives:

• Identify the HTTP method in a request.
• Identify the path or URL in a request.
• Name at least one common request header and explain what it does.

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A letter needs an action, an address, and a note on the envelope

When the browser sends a request, it is not just yelling "give me the page!" It writes a formal envelope. That envelope has three parts: what it wants to do, where it wants to do it, and a few extra notes for the server.

In HTTP, those three parts are called the method, the path, and the headers ¹.

Explanation

Method: the action

The HTTP method is a single word that says what the browser wants. The most common ones are:

• GET — "Please send me this resource." ²
• POST — "Here is some data; please accept it." ³

Most page loads use GET.

Path: the address

The path is the part of the URL that comes after the domain. For https://example.com/about, the path is /about. In the request itself, the browser writes only the path, because the domain is already sent in a header ¹⁴.

Headers: the extra notes

Headers are metadata lines that come after the request line. Each header has a name and a value, separated by a colon. For example:

Host: example.comUser-Agent: Mozilla/5.0Accept: text/html

The Host header tells the server which domain the request is for. The User-Agent header tells the server which browser is asking. The Accept header tells the server what kind of content the browser can handle ¹.

Worked example (follow along)

Here is a complete GET request for https://example.com/about:

GET /about HTTP/1.1Host: example.comUser-Agent: LearnBrowser/1.0Accept: text/html

• GET is the method.
• /about is the path.
• Host: example.com, User-Agent: LearnBrowser/1.0, and Accept: text/html are headers.

Your turn (faded example)

Underline or label each part of this request:

POST /contact HTTP/1.1Host: example.comContent-Type: application/x-www-form-urlencoded

• Method: POST
• Path: /contact
• Headers: Host: example.com and Content-Type: application/x-www-form-urlencoded

Summary + what's next

A request is an envelope with three parts: the method (what to do), the path (which resource), and the headers (extra notes). In the next lesson, you will look at the server's reply.