Congratulations on getting an interview! Whether it is via phone, skype, or in person, on campus or at the employer's location, 30 minutes or an all-day process, scheduled for the next day after a job fair, or scheduled well in advance, for an internship or post-grad job, being prepared is the key to success.
Interviews occur in a wide variety of settings and formats. Your contact person representing the employer organization should always provide you schedule and location information.
Use the menu provided here to become familiar with formats and settings. And most important: research the employer thoroughly so that you present yourself as a fit with the employer.