On FlyerTalk, when you see a wiki icon next to a thread name within a forum index, it indicates that the thread has a Wikipost. On FT, wikis may contain a summary of the thread discussion, topic FAQs, instructions for proper use of that particular thread, links to related topics, etc.

If you're not seeing the wiki at the top of the thread, it may be hidden or minimized. Just look for a dark blue bar above the "Post Reply" button that says Wikipost, and click the "+" button on the far right side of that bar to display the wiki.