Online Mode or Offline Mode Server?

Many people have probably heard of Online Mode and Offline Mode Cracked Minecraft Servers, but not everyone completely knows what it does. Online Mode

Testing an Application in Offline Network Mode

Can someone tell me why papers documentation says set online mode same as bungeecord server? I always thought all servers had to be in offline mode when used with a proxy.

How to allow cracked players to join your Minecraft server (Disable Online Mode) - Xgamingserver

Working in Offline mode - Altair Community

Internet connectivity, offline grace period, and reminders

Switch Online/Offline

AutoMerge system framework. AutoMerge supports both offline and online

Offline to Online Switch on a Minecraft Server – Medo's Home Page

How to Play Minecraft Offline: 11 Steps (with Pictures) - wikiHow