Most interviews are face-to-face. Initial telephone interviews are sometimes used to narrow down the list of applicants.
Interviews are usually structured. All applicants are given a set of questions or activities, on which they are assessed.
Unstructured interviews are less formal, allowing you to direct the interview and focus on your strengths.
Self-advocacy interviews allow a set time (30-45 minutes) to present yourself to a panel of interviewers. These are not used very often, and tend to be for more senior roles.
You could be asked to attend a single or series of interviews. Graduate recruitment often involves more than one interview.
Late round interviews help employers refine the list of applicants. Often a more senior staff member will conduct second or later round interviews and the questions may become more difficult.
Some interviews involve just you and the interviewer. More commonly, a panel of people will interview you.
Some organisations interview groups of applicants. This enables them to see a large number of people and to narrow down a short-list. Group sizes vary. Employers will not always tell you how the group interview will work or what they are looking for.
There are several styles: