Problem → Agitate → Solve. The most direct-response of all copy formulas.
PAS starts by naming the prospect's problem, agitates it (makes them feel how painful it is), then offers your solution. It works because it mirrors how people actually think about buying: they're not buying a product, they're buying out of a problem. PAS forces you to describe the problem vividly enough that the reader pays attention, then offers the exit.
PAS is tighter and more punchy than AIDA. For emails, ads, and short-form content, it usually outperforms. Use PAS when you need to be direct. Use AIDA when you have more room to unfold.