You use hundreds of URLs every day.
You probably never look at them.
That's fine, most of the time. The browser hides the ugly parts, and a link preview shows a title and an image instead.
But the moment you need to share a link, track a campaign or fix a broken page, the address suddenly matters.
So what is a URL, exactly?
It's the full address of one specific thing on the web. And every part of it has a job.
This guide answers "what is a URL?" by taking a real one apart, piece by piece. Then it looks at why some URLs get so long, and where a short link fits in.
What is a URL?
A URL is the address of a resource on the internet.
That resource can be a web page, an image, a PDF, a video or an API endpoint.
The browser reads the URL and knows three things:
- how to talk to the server;
- which server to talk to;
- what to ask it for.
That's the short answer to "what is a URL".
The longer answer is in the parts.
What does URL stand for?
URL stands for Uniform Resource Locator.
The name is surprisingly literal.
It's uniform, because every URL follows the same general syntax. It points to a resource. And it locates that resource, meaning it tells you where to find it.
You'll also see the term URI, Uniform Resource Identifier. Every URL is a URI. For everyday use, the difference doesn't matter much.
URL meaning in plain English
If you're searching for the URL meaning without the jargon, think of a postal address.
The country, the city, the street and the house number each narrow things down.
A URL works the same way. The domain gets you to the right building. The path gets you to the right room.
The parts of a URL
The easiest way to answer "what is a URL?" is to take one apart:
https://blog.example.com:443/guides/url-basics?utm_source=newsletter&utm_medium=email#parts
It looks like one long string.
It's actually seven or eight separate pieces.
1. Scheme
https://
The scheme, sometimes called the protocol, tells the browser how to connect.
Today that's almost always https, the secure version of http.
Other schemes exist. mailto: opens an email. tel: starts a phone call. But on the web, you'll mostly see https.
2. Subdomain
blog.
The subdomain sits in front of the main domain.
Companies use it to separate parts of a site. blog.example.com, shop.example.com, help.example.com.
www is also a subdomain. It's just the most common one.
3. Domain
example.com
This is the part people remember.
It has two pieces. The second-level domain (example) is the name someone registered. The top-level domain (.com) is the ending, like .org, .io or a country code like .ro.
The domain is also what security tools and AI agents check first. That's why it matters so much when you can't see it.
4. Port
:443
The port is usually invisible.
Browsers assume port 443 for https and 80 for http, so you almost never type it. You'll mostly see a port in development, like localhost:3000.
5. Path
/guides/url-basics
The path tells the server which page or file you want.
It often mirrors the structure of the site. A folder, then a page inside it.
6. Slug
url-basics
The slug is the last readable part of the path.
It identifies one specific page in words instead of numbers. People search for "slug URL" because content systems like WordPress ask you to set one when you publish.
A good slug is short, lowercase and uses hyphens. This article's slug is what-is-a-url.
7. Query string and URL parameters
?utm_source=newsletter&utm_medium=email
Everything after the question mark is the query string.
It's made of URL parameters. Each parameter is a key=value pair, and the pairs are joined with &.
In this example there are two:
utm_source=newsletter;utm_medium=email.
Parameters don't point to a different page. They pass extra information to the same page. A search term, a filter, a sort order, or campaign tags.
This is the part that makes URLs long. More on that below.
8. Fragment
#parts
The fragment, or anchor, starts with #.
It points to a section inside the page. Click a table of contents link, and the browser jumps to that heading.
There's one detail worth knowing. The fragment is never sent to the server. It stays in the browser.
URL vs. slug vs. permalink
These three terms get mixed up a lot, usually right after someone asks "what is a URL?"
Here's the simple version:
- the URL is the full address;
- the slug is the readable name at the end of the path;
- a permalink is the URL a page is meant to keep permanently.
The word permalink comes from blogging. The idea was that a post's address shouldn't change once it's published, so other people can link to it safely.
That idea is still good advice.
Changing a URL breaks every link that points to the old one. Unless you set up a redirect, anyone clicking an old link hits an error page.
What makes a URL good?
Once you know the answer to "what is a URL?", the next question is what makes a good one.
There's a lot of advice about SEO friendly URLs.
Most of it comes down to one thing: a person should be able to read the URL and guess what's on the page.
Compare:
example.com/p?id=48213&cat=7
with:
example.com/guides/url-basics
The second one tells you something before you click.
A few habits help:
- use words, not IDs;
- keep it short;
- use lowercase and hyphens;
- avoid changing it after publishing.
I'd be careful not to overstate the SEO side, though.
A clean URL helps people understand a link. It's not a magic ranking lever. Search engines care much more about what's on the page.
Why URL parameters make links so long
Now back to the query string.
If you run campaigns, you probably add UTM parameters to your links. They tell your analytics tool where a visit came from.
A normal destination:
https://example.com/spring-sale
The same destination, tagged for one newsletter:
https://example.com/spring-sale?utm_source=newsletter&utm_medium=email&utm_campaign=spring_launch&utm_content=header_button
The page is exactly the same.
The URL is three times longer.
That's not a problem for a browser. It's a problem for people.
A URL like that breaks across lines in an email. It gets cut off in a bio. It turns a QR code into a dense block that's harder to scan. And nobody is going to type it from a poster.
But you still want the tracking.
If you're setting up UTM tags across several channels, I wrote a separate guide on how to measure a marketing funnel with them.
Where a short link fits
This is where a short link becomes useful.
Instead of sharing the long URL, you share:
zee.gl/spring-sale
When someone opens it, the short link redirects them to the full destination, UTM parameters included.
The visitor sees the short version.
The destination still carries the campaign information.
What is a redirect?
A redirect is an instruction that says: the thing you asked for lives at a different URL, go there instead.
That's the whole redirect meaning.
The browser follows it automatically, usually in a fraction of a second.
A short link is really just a stored redirect. zee.gl/spring-sale is a short URL whose only job is to send you to a longer one.
With ZA.GL's URL shortener, you can fill in UTM fields when you create the link, and they're appended to the destination for you. You can also pick the alias yourself. In practice, that alias works like a slug for the short link.
And because the redirect happens on a link you control, you can count the clicks before the visitor reaches the page.
What a short link won't do
Let's be honest about the limits.
A short link doesn't improve your rankings.
Search engines follow the redirect and look at the destination. The page is what ranks, not the short URL in front of it.
So if you're linking between pages on your own site, use the direct URL. It's transparent, and there's no extra hop.
A short link also hides the destination. That's a real trust problem. This is why ZA.GL shows a preview page with the destination domain, the connection status and how other visitors rated the link.
Short links are for sharing and tracking.
Not for SEO.
So, what is a URL, really?
It's an address.
But it's an address with structure, and each piece does a specific job:
- the scheme says how to connect;
- the domain says where;
- the path and slug say which page;
- the URL parameters pass extra information;
- the fragment points inside the page.
Once you can read those parts, a lot of things make more sense. Why some links are long. Why changing a URL breaks things. Why a tracking link still works after it's been shortened.
A URL isn't just a location. It's a set of instructions.
Most of the time, you don't need to think about it.
When you do, it helps to know what you're looking at.
If you want to see it in practice, shorten a tagged link on ZA.GL and compare it with the original.
What is a URL? FAQ
What is a URL in simple terms?
It's the address of something on the web, like a page, an image or a file. Your browser uses it to find and load that thing.
What does URL stand for?
Uniform Resource Locator. It locates a resource on the internet using a standard format.
What is a URL used for?
To find and share things on the web. Every link you click, every page you bookmark and every QR code you scan is a URL underneath.
What is a URL vs. a domain?
The domain is only one part of a URL. In https://example.com/pricing, the domain is example.com, and the full URL also includes the scheme and the path.
What is an example of a URL?
https://example.com/guides/url-basics is a URL. It has a scheme (https), a domain (example.com) and a path (/guides/url-basics).
What are URL parameters?
URL parameters are key=value pairs after the ? in a URL. They pass extra information to a page, like a search term, a filter or campaign tags.
What is a slug in a URL?
The slug is the readable part at the end of the path that names a specific page. In example.com/blog/what-is-a-url, the slug is what-is-a-url.
Is a short link bad for SEO?
No. Search engines follow the redirect and evaluate the destination. But a short link doesn't help rankings either. It's a tool for sharing and tracking.