Hi Melanie,
It's a functionality that forms part of the platform that we use. We have instant messaging disabled on this site to protect privacy but it can be used as a quick link to "follow" those members whose posts your find most useful.
If you visit the User CP section of the site - in the left hand navigation there is a buddy/ignore list link. Click on this. You can then add the usernames of the members you'd like to follow. Then, in future if you click on this link, click on the name, you can find their latest threads and posts.
Kindest regards,
Julia
