>>592Nope! It's by the number of unique IPs
Two additional important points:
1) They have to be on the board to count.
2) They have to have been in the last 72 hours. (Source:
https://github.com/ctrlcctrlv/infinity/blob/a97b08db42cd06bf75d353153b55a235dff281b2/templates/8chan/boards-tags.html#L78)
Because of 1), even if a post was made in the last 10 minutes, if it gets deleted (either manually by the poster or a moderator, or automatically by being pushed off of the board by new threads) it will stop counting.
This is why you can spam a board's entire catalog with new threads, and its Active Users will drop to 1 (or you can nuke the catalog and it'll be 0), dropping it like a rock from the top 25 list, this has sort of happened a couple of times with boards like /furry/ and /int/.
Bui demonstrated how you can manipulate this with his botnet spamming of /superduperepicmemerinoslolxd/, /pokepaws/ and /polidicks/ to the top 25. He spammed a 25 page catalog with new threads, each one being from a Unique IP from his botnet. You can have 15 threads on each page, and with 25 pages you can get 375 threads (375 unique ips) which easily places you around the middle of the top 25 (this is the sort of area /polidicks/ and /pokepaws/ reached in the top 25, they also topped at ~450 Unique IPs before falling, with a base of 375 IPs that would mean there were around at least 75 additional visits from anons that may have not been from Bui's botnet, or Bui decided to spam by posting in threads instead of creating new threads).