How are views calculated?

I’m curious how thread views are calculated. It doesn’t seem that I can drive the count up by opening the thread multiple times, so it counted only once per username, or per IP address for people who aren’t registered, or some other way?

(Googling how are views calculated straight dope didn’t provide an answer but did pull up a journey down the rabbit hole in the form of a Storm Front thread from 2002.)

Views are updated at :57 of every hour.

Forgot the other condition.
During the first hour, the views will always be 1 more than the number of replies.
When I post this, there will be 2 replies and 3 views.

Once it update for the first hour, that no longer applies.

I’ve always wondered if crawls by search engines bump the counts.

It doesn’t seem obvious that they do in new threads, but when someone reactivates a zombie, there are usually a huge number of views. I have to wonder whether that many people actually read the thread while it was dormant or whether that was just spiders crawling the web.