What is a virtual host or server block?

What this card says

Short answer

A virtual host (server block) maps a hostname or port to a site folder, so one machine can host several sites.

Example

On one server: shop.example.com and warehouse.example.com, each with its own root folder and log files.

Say it in the interview

“A server block maps a hostname to a site root, so one box runs many sites with separate logs.”

Why it matters

Separate roots and logs keep sites isolated, so one site’s problem doesn’t leak into another.