There are several wikis available.
- There is a community – created wiki. It has some how-to articles, some device descriptions, a FAQ, a first bug reports section, and the always useful quick browse lists for smart apps, device type handlers, and project reports. If anybody in the forum refers to “the wiki” they probably mean this one.
This is a full-featured wiki, and community members are encouraged to register for an account and add additional articles or update ones that have become outdated. 
http://thingsthataresmart.wiki/index.php?title=ThingsThatAreSmart_Wiki
- Webcore has its own forum and wiki.
- The official SmartThings knowledgebase and support pages are at:
https://support.smartthings.com/hc/en-us
- WikiPosts section of this forum.
This is where you are now. 
A number of the FAQ posts from different sections of the community forums have now been combined into one wikiposts section. This is usually referred to as “the wikiposts section of the forum” to distinguish it from the community – created wiki in 1) above.