Session is a period of time during which a user with a unique IP address performs any actions on the website. Survicate session lasts 30 minutes - meaning any activity performed in this time will be counted as one visit. Any number of times a user enters a website within this time period will be considered one visit.
If the visitor comes back to the site after 30 minutes from the initial visit, it will be counted as a separate visit.
In case of any session-related targeting options enabled, keep in mind that the session lasts 30 minutes and this is the time after which you need to test surveys. They won’t be displayed upon every visit.