I quickly come across the term for a fancy way of saying "interviewing a game developer".
Well an AMA is a public interview of anyone, not just game developers. If you plan to participate in one, or even just read the results of one, it's probably worth it to look at a few to get an idea of the format. There are two main subreddits dedicated to AMAs:
r/AMA and
r/IAmA. There's no hard-and-fast rule about what goes where, but IAmA tends to be the more legit and helpful one these days.
Some examples:
Chris Hadfield
Buzz Aldrin
They start with a paragraph introduction, along with "proof", which usually consists of a concurrent post on a social media account (often Twitter) known to belong to the person in question. Questions come below and the presentation is threaded (replies to comments are indented underneath the comment, and can be nested indefinitely.) The comments made by the poster (the subject of the AMA) have their name bolded or highlighted, so they can be easily identified on a quick scan through the thread. You can sort the replies by "best" or "top", which is usually good. Sometimes it works better (particularly for a less notable person with only a few interlocutors) to sort them by "old", so you can see the conversation develop as it occurs/occurred. There's often some reddit insider shenanigans in the comments, and it's best not to read very deeply into comment threads if you value your sanity and continued commitment to humanity's welfare.
HarvesteR's is scheduled for September 23 at 9:30am PST.