WebTool

Network & Ops · Ch. 1

URL Anatomy: Scheme, Port, Path, Query String, and Fragment

WebTool Team · Published 2026-09-08 · URL / HTTP / Frontend / Networking

A complete URL has seven parts: scheme, host, port, path, query string, and fragment (plus optional user info). The browser only sends "everything before the fragment" to the server — whatever follows # never leaves the browser. Paste a complex URL into our URL parser to see it broken down segment by segment.

Segment by segment

https://user:pass@example.com:8443/path/to/page?id=1&lang=zh#section-2
\___/   \_______/ \_________/ \__/ \_________/ \___________/ \_______/
 scheme   user info    host     port    path        query       fragment
Part Meaning Notes
Scheme https, http, ftp, etc. Determines the default port and security semantics
User info Deprecated; seen mostly in documentation Never use it to pass credentials
Host Domain name or IP Case-insensitive
Port Defaults when omitted (http 80 / https 443) Default ports are not displayed
Path Resource location on the server Starts with /
Query string ?k=v&k2=v2 Pairs separated by &; values need URL encoding
Fragment Everything after # Never sent to the server; commonly used by frontend routers

Absolute vs. relative paths

When the page is at https://a.com/docs/guide/:

  • <a href="page2"> → https://a.com/docs/guide/page2 (relative to the current directory)
  • <a href="/page2"> → https://a.com/page2 (relative to the root)
  • Watch the trailing /: /docs/guide and /docs/guide/ resolve relative paths differently — a missing slash on a directory page is a classic cause of resource 404s.

The three most common pitfalls

  1. Unencoded & in the query string: a value containing & gets split into two parameters (see Chapter 3 of the Encoding series).
  2. Lost fragments: if a server-side redirect doesn't explicitly preserve #..., the fragment disappears — it was never in the request, so the server has nothing to forward.
  3. Case confusion: hostnames are case-insensitive, but paths and query strings are case-sensitive — /Page and /page are different addresses, which matters especially on Linux servers.

Last updated: 2026-09-08