While I'm sure Joe has a deeper, ANSI definition for these terms, I believe their simplest usage is as a reference point. In a LEFT join the LEFT table is the preserved table and the RIGHT is unpreserved. The reverse would be true in a RIGHT join. So in discussion it doesn't matter if we're talking about LEFT or RIGHT joins, we'll know which table is which using these two terms. Like in a car, we don't reference left and right sides because that's relevant to whether or not I'm looking at it from the back or from the front. Of course, referencing driver-side and passenger-side is different based on the country you live in. Now that I think about it, like boats, I'm all for using port and starboard for cars. 😛