The interviewer wants to know that you have clearly thought through your decision to leave your current job, and that you know what you want out of your next role.

Never use this question as an excuse to complain about your current or previous employer, as it will make you sound unprofessional! Instead, take the opportunity to explain areas in which you’d like to be more challenged, projects you haven’t had the opportunity to work on, or simply elaborate on why this move is right for you at this time. Focus on the positive aspects of what else you have to offer professionally and how it fits within the role you’re applying for.