Rules, House Rules, Rulings, Errata

Additional information:

> Errata can become Rules in new reprints (mostly in the interest of balance)

> Rulings can become House Rules by being written down or otherwise socially accepted by the group as future reference (mostly in the interest of fairness)

What is balance? What is fairness?

Balance is when the math of a game works out. It's when neither party is too likely to win.

Fairness is when the DM doesn't put mechagodzilla in front of a level 1 adventuring party. It's when they don't cheat, or don't cheat too much. It's when they make a ruling, and then stick to it. Fairness is when the expectations of all players are met.

The composite definitions are therefore that:

Errata can be integrated in the main corpus of rules to keep the math of a system tight and working

Rulings usually become house rules to respect the expectations of how the game should work