First, they had me do these personality test/game things online and do a few problems on Hacker Rank that were fairly easy. Then I interviewed in person at the Grace Hopper Celebration. I'll start this by saying that although they are a tech company, they were using paper records to keep track of the schedule of interviewers for the day. So when I showed up for my interview with my email confirmation, they didn't have me on their paper list and weren't expecting me. They rescheduled me to interview the next day, and I watched the woman enter me in the system and got a confirmation email saying that I was set. Then I showed up the next day, and I'm still not on their list. Thankfully, the woman recognized me and confirmed I was supposed to be there. She directed me to the booth where my interviewer was and told me to go in once the interviewer finished with the person she was currently with. The interviewer then held the person before me 20 minutes into my 30-minute interview, which was ridiculous. So then, as soon as the other girl left, I stuck my head into the booth and asked if she was ready for me, and of course, she had no idea that I was scheduled because this "tech" company is still using a paper list for their schedule that was subject to change. The interviewer got really stressed and flustered and went ahead and tried to give me the interview, but tried to condense my 30-minute interview slot into 10 minutes. She was extremely rude and unprofessional and would make faces or noises if I wasn't answering her questions fast enough or well enough. She then decided to just give me a whiteboard question, but while I was trying to talk through it and work through it, she would start rushing me or butt in, breaking my train of thought, and immediately just tell me I was wrong without letting me even get a complete thought out. Eventually, I turned to her and told her to stop and that she was stressing me out, and she apologized and told me to continue. However, she kept doing it, so I eventually just closed the marker and told her I was done. She then told me that she sees my thought process and that I "could be hopeful," but I wasn't holding my breath. After the conference, the recruiter followed up, and we scheduled a 30-minute behavioral interview over WebEx. My interviewer was, of course, 15 minutes late, and at this point in the process, I was fed up with how rude and unprofessional everyone on their end had been throughout everything. It was, overall, the worst interview process I have ever had, and I'm honestly glad they didn't give me an offer because I would have rejected it. Who would want to work for a company that's so disorganized and full of rude and unprofessional people? This whole thing was a waste of my time and energy.

Explain to me what an API is.