In my column this week I take a look at some opening lines, but classic and contemporary, in which one side (always White, in the examples) makes a move that looks like an obvious, beginner-like tempo-waster (generally Bb5, in a position where the bishop is immediately or soon kicked by a Black pawn) turns out to be a clever way of obtaining an otherwise unavailable benefit. Some of you might find this old hat, but hopefully some readers will find this eye-opening, at least on account of the rich diversity of examples. (Feel free to add more in the comments - there were plenty more I omitted due to space limitations.)