An informational interview is a meeting to learn about the real-life experience of someone working in a field or company that interests you. It's not a job interview, so it's important to keep focused on getting information, not a job offer.
One of the best sources for gathering information about what's happening in an occupation or an industry is to talk to people working in the field. This process is called informational or research interviewing. An informational interview is an interview that you initiate – you ask the questions. The purpose is to obtain information, not to get a job.