Paper? Spigot? WTF? Aren't we just playing Minecraft?

Yes. Mostly.

The "stock" Minecraft server released by Mojang has notoriously poor performance when more than three or four players are on the server (we say "it doesn't scale well"). It also does not support server plugins that add useful functions to the server. (Yes, it supports mods, just like single player, but that's a different kettle of fish).

Originally there was a third party server called Bukkit , which offered programming libraries and interfaces (APIs) to enable the creation and use of plugins. But Bukkit is not optimized for performance.

Another group took the base Bukket server and started their own project (they "forked" Bukket) called Spigot. Spigot is a Minecraft server with a number of optimizations to reduce server workload and improve efficiency.

That wasn't enough optimizing for yet another group of folks, who decided to develop their own set of optimizations, improvements and fixes (don't ask Anna about the fixes unless you want a rant) which they layer on top of Spigot. This is the Paper project.

Ravencraft normally runs on Paper. However, because Team Paper can't start their work until Team Spigot releases their work, when there has just been a major update, we will often run Spigot for a time in order to get onto the latest version of MC faster.

Here is a tongue-in-cheek performace comparisson of "stock" MC server, Spigot and Paper

Server	5 Users	15 Users	30 Users
Stock Minecraft	Lagging	Weeping in a corner	Stick a fork in it, it's dead
Spigot	Running fine	Breathing hard: the lag is real	Sweating bullets but still up
Paper	There are users on?	Getting down to business	Busy. Very busy.