Network and addresses
Ping (latency)
The time for data to reach the server and come back. Depends above all on distance.
Ping is measured in milliseconds: from Moscow to a Moscow server 1–5 ms, to Germany 40–50, to the USA 120 and more. For a website the difference is barely noticeable; for games and voice it is critical.
The simplest way to cut ping is to pick a data center closer to your users. Many providers publish test IPs so you can check latency before buying.