What is a URL, really?

Every URL is a structured address — learn to read it

⏱ Est. ~4 min

01 · Read

You've been clicking URLs your whole life. But as an engineer, you need to read them — not just click them.

Every URL is built from different parts, and each part has a specific meaning. Once you can break down a URL, you can figure out any API, debug any request, and build any network feature.

💡 Picture thisA URL is like a mailing address. The protocol is the shipping method (air vs ground), the host is the street address, the path is the apartment number, and the query string is a sticky note on the envelope with extra instructions.

Key points

URLs are structured — each part has a name and a purpose
The query string (?key=value) is how you pass optional parameters
A path like /users/42 means "resource users, item 42"
The same host can have thousands of different paths

02 · Code example

Let's break a real URL into its parts.

Full URL

https://api.github.com/users/torvalds/repos?per_page=5&sort=updated

Protocol

https://

"How to talk" — encrypted HTTP connection.
Always https:// for real APIs (not http://).

Host

api.github.com

"Who to talk to" — the server's address on the internet.
DNS translates this to an IP like 140.82.121.6.

Path

/users/torvalds/repos

"What to ask for" — the specific resource on that server.
Like a file path, but for API resources.

Query String

?per_page=5&sort=updated

"Extra options" — key=value pairs after the ?.
per_page=5 means "give me 5 results".
sort=updated means "sort by last updated".

The ? marks the start of the query string. Each parameter is key=value. Multiple parameters are separated by &. The server reads each one as an option or a filter.

03 · Drag to sort

Figure out the correct part for each URL fragment below.

(This section is interactive — please enable JavaScript.)

04 · Quiz

In the URL https://api.example.com/products?category=shoes&limit=20, what does limit=20 do?

Connects to port 20 on the server
Passes 'limit' as a query parameter with the value '20' — the server decides how to handle it
Limits the server's CPU usage to 20%
Sets the URL's maximum length to 20 characters

Other lessons in this chapter

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