At a hiring event you mingle, and if the interest in each other is present, someone will put you on the interview list. A few days later happens the intense, four-rounds interview with each round taking about an hour, in which after the second (or in some case after each) round they may let you go. You are only considered as a potential hire if you make it until the end of all rounds. The first interview is informal and serves multiple purposes. It is both for you to ease into the process and help you get through the interviews without the usual initial anxiety with which most people arrive to an interview, and secondly it's the cultural fitness check: are you the kind of person who fits into company culture? The following rounds are the professional interviews. There are discussions of past experience, problems to solve, a system to design and write code for both general and specific to the areas you are about to work with. Some of the problems are difficult, but the goal is not for you to be able to perfectly solve everything. They want to see if you meet an expectation of course, but other than that they are looking for problem solving strategies and your strengths and weaknesses, generally speaking: how would you do on the job? E.g.: if you don't know something, you still should present your strategy of solving the problem; you might get to do a Google search but at least ask questions from the interviewer and proceed with the new information.