This question seems simple, so many people fail to prepare for it, but it's crucial. Here's the deal: Don't give your complete employment (or personal) history. Instead give a pitch-one that's concise and compelling and that shows exactly why you're the right fit for the job. Start off with the 2-3 specific accomplishments or experiences that you most want the interviewer to know about, then wrap up talking about how that prior experience has positioned you for this specific role.