A web server is a computer dedicated to storing web pages securely and delivering them to users when requested.
A website developer would upload their website to a web server using FTP.
Web servers are switched on 24 hours a day, ensuring the stored web pages and resources are always available.
To ensure web pages are served to multiple simultaneous users as fast as possible, web servers have very fast/dedicated internet access.
Like all devices connected to the internet, a web server will have an IP address.