When viewing a user's profile you can see a count of the number of times that they've visited and also the date that they were last active on the community. Visits are a bit of a fuzzy statistic that can't ever be 100% accurate because we have no true way of knowing if a person is sitting at the computer.
If you are interested in knowing when a visit is calculated, in general a user had to be away from the site for at least 20 minutes. What away from the site means is determined by the following:
- If the user closes the site then they will be considered away from the site so the next time they browse to the site a new visit may be incremented.
- If the user leaves the site open they will be considered away if the site isn't in their active tab. This is to account for users that may have a long discussion open for more than 20 minutes. If you leave your browser open over night then you likely won't trigger a new visit.
This methodology is a heuristic that tries to balance accuracy against the reality that people often leave browser tabs open for a very long time.