Understanding the purpose of any interview will help alleviate some of the stresses interviews usually cause and will also help to increase the chances of success.
Interviews are designed for both employers and candidates to learn more about each other. Understanding the knowledge and skills required to do the job is the typical first step. In addition, employers want to know if a candidate is a good fit for the organization.
As a candidate, you will want to know if the organization will meet your expectations. Whether you are interviewing for an internship or a job, it's important to learn about the employers expectations and how they see you fitting in to the overall mission of the organization. The key to any successful interview is practice, practice, practice. Practicing out loud is also a great strategy to help improve the outcome of the interview.