Domain names and hosting
Web sites come in many shapes and sizes, but they all need two things: a domain name and a hosting arrangement.
The domain name is the name that is typed to reach the web site: for this web site it is www.silverfen-web.com.
Hosting refers to the fact that a web site is actually a collection of files on a computer attached to the internet, with some web-serving software to serve those files when a person wants to see the web site. In principle this can be done from any computer attached to the internet. In practice it makes most sense for this to be done by an internet service provider because they have fast connections to the internet and have technicians in attendance 24-hours a day, enabling any problems to be sorted out quickly. In effect the hosting charge is renting some space on a suitable computer.
If a web site uses a content management system then it's normally necessary to have a database involved as well. Typically this means either PostgreSQL or MySQL. The latter usually needs something like phpMyAdmin to provide an interface for altering it, so content management systems nor ally need these extra hosting facilities.
The costs of domain names and hosting are modest and usually a small proportion of the cost of a web site.