What is the difference between a URL, Domain, Subdomain, Hostname etc.?

The abbreviation “URL” is short for “Uniform Resource Locator” and is commonly used to refer to a website or internet-address, while the actually intended goal is usually a directory or a specific path.

The structure and components of a URL

A URL is usually made up of several parts. To understand the structure and the components, we will dismantle the following example URL:

Aufbau und die Bestandteile einer URL: http://www.youtube.com/watch?v=QhcwLyyEjOA
Structure and components of the URL http://www.youtube.com/watch?v=QhcwLyyEjOA
  1. The Protocol in use – in this case: HTTP (Hypertext Transfer Protocol) There are also other protocols like HTTPS, FTP and so on.
  2. The Host or Hostname: www.youtube.com
  3. The Subdomain: www.
  4. The domain name (Domain): youtube.com
  5. The Top-Level-Domain (a web-address suffix): .com (also known by the shorthand TLD)
  6. The Path: /watch A path will usually refer to a filename or folder (directory) on the webserver (for example “/folder/file.html”)
  7. Parameter and value: v (Parameter), QhcwLyyEjOA (Parameter value) Parameters are initialised by the “?” inside the URL.
    In our example, the parameter name is “v” and its value is “QhcwLyyEjOA” (Parameter name and Parameter value always have the same structure: Parametername=Parametervalue) Parameters are sometimes used for session IDs.

General language use

If we talk about a URL, we usually mean the web path to a directory (http://www.domain.com/a-directory/) or a file (http://www.domain.com/documents/study.pdf) on a website.

It is, of course, not completely wrong to talk about a URL and simply mean the host- or domain name of a website, but we should try to use the correct terminology.

What are URLs with incorrect syntax?

URLs with incorrect syntax are URLs that are not built correctly. An example of this is http::///example.com. Such a URL cannot be read by a browser and results in an error message. Correct URLs are also extremely important in links.

How do I avoid very dynamic URLs?

Dynamic websites differ from static websites in that they are not permanently stored on a server, but are created on demand. In short, an application creates the page using data from a database to match a user’s request. Dynamic URLs can often be identified by the use of URL parameters.
An example of this is:


Dynamic URLs have many advantages, from being easy to create via content management systems to being less hassle to manage. However, try to keep URLs short and avoid using unnecessary parameters so that search engines can read them better. Also, it is advisable not to hide any important parameters. Google advises against the so-called rewriting of dynamic URLs, by which they are converted into static URLs.