Data center — a facility that houses servers run by various organizations (like web hosting companies).

Name server — a service that translate the human-readable domain name into the machine-readable IP address.

Overselling — a practice of selling more server hard disk space and bandwith than is actually available at the given moment. So, you have 10 GB, but you sell 20 GB. You’re oversold by 10GB. This is a common practice on shared plans as most accounts never use more than 10% of their allocated resources.

Proxy — a software that acts as a gateway between the surfer and internet.