Employees who love their jobs naturally recommend their company to their friends and peers. The same is true for people in leadership positions -- people naturally try to bring on board talented people they previously worked with. They've built relationships, developed trust, and shown a level of competence that made someone go out of their way to follow them to a new organization.
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.
Laid off is not fired: If you were part of a layoff, this is different from being fired. It was likely a financial decision by management, and you were part of a group that was targeted as part of budget cuts. Layoffs are typically not personal -- they are just business. Hiring managers know this (and likely have been involved in one at some point in their careers).