More than any other question these six words have the power to make or break your job interview.
Why do you want this job?
It seems simple enough: "I'm a financial services recruiter, you are a financial services recruiter - it's a match made in heaven, lets go share the commission checks". Unfortunately (or perhaps fortunately) not!
If an interviewer asks nothing else about you but this question, here is some of what they could learn about you in the answer:
Did you prepare? Have you researched the job opportunity, the interviewer, the company benefits, the company environment, the career path, the typical goals of employees?
Are you self aware? Can you articulate why the role, company and opportunity suit you specifically in terms of career stage, learning opportunities, responsibilities?
What have you achieved before? Are you capable of drawing parallels between the successes you have had and those necessary to the role available? Can you show how past successes for another employer will help you create future successes for this employer?
If you can imagine there are 5 candidates being interviewed whom all have the technical skills for the role and broadly similar backgrounds (not unlikely) it is the most robust, relevant and true answer that wins the day. Even in a skills short market Employers worth their salt will look to discern on the basis of fit, culture and work style, all of which are evident in the answer to those six words.
There is more, much more I am sure, that can be articulated, but isn't that enough? Like a good boy scout, candidates should always be prepared.