Employers often contact candidates by phone or email, but you may also get a text message or a printed letter asking you to an interview.
You will be informed of who you will be meeting with through email, letter, or phone call. You may be allocated a certain time for your interview, or you may be given a choice of schedules.
If the employer asks you to prepare materials, such as a lesson plan for a teaching position, you will be told of what to bring and how to prepare.
You should also be informed of the interview format. For example, if you are meeting with a group of people rather than a single interviewer, the employer should notify you.