What are a free shard and PTS?

A free shard is an unofficial Lineage 2 server: it is run neither by the game developer nor by an official publisher. Almost every server in the listings is a free shard.

PTS is a server on the original server files of the game. Other free shards run on emulators written in Java: an emulator reproduces the original server, but some mechanics may differ. The server website usually says what it runs on.