Applied online for an internship for research & development engineering. The interview process took around 2 months in total, split between 4 stages: online, one informal, one formal, and one on-site. I took two standardized tests online, one behavioral and one aptitude test. After passing both, I was given a short (~20 min) informal interview by a campus recruiter. About a week later, I was offered a second interview. Since I was not available at any of the times available for a live interview, they offered to schedule a phone interview for the second round, which lasted around 45 min and consisted of behavioral questions. Two weeks later, I was invited to a final interview stage on-site in Cincinnati. The company flew in interns applying to the position, and we were told that positions were available for each of us/we weren't competing for the same spots. A current employee was assigned to each candidate as a host to welcome us. The next day lasted around 7 hrs and consisted of 3 separate interviews, 2 behavioral and one case study about a struggling product. About a week later, I was given an offer.