The goal of the interviewer is to hire the right person for a specific job. In order to determine if you are the right person they seek the answers to three major questions:
Can you do the job?
Will you do the job?
Will you fit in?
Your goal is to get hired as the right person for a specific job. The interview is your chance to persuade the employer that you:
Have the skills & knowledge to do the job
Have the interest & desire to do the job
Have values that fit the culture
You and the employer have the same goal - to fill the position with the right person! To achieve this goal you need to clearly present evidence that you are the right person who can and will do the job and will fit in.