If you have a gray box for categories in your wiki pages it is because you have not setup your term store. (Categories are not working in wiki pages)
How to setup term store for wiki page. (setup categories)
Setup Term store in Central admin (changes in Central Admin)
- Go to Central Admin -> Manage Web Application –> Select your Web app –> Select Service Connections
- Select Managed Metadata service
- Setup your term set here
Setup Metadata in the Site (changes in site setting)
- Activate feature: Select site settings -> manage features -> “Metadata Navigation and Filtering” – click activate
- Site Actions > Site Settings > Term store management (under Site Administration)
- You can add you terms here
Setup Categories in the Wiki page (changes in library Settings)
- Library settings page of your “Pages” library and select Metadata navigation settings
- Configure Navigation Hierarchies” select “Wiki Categories” and click “Add” and “OK”
-
Library setting -> Enterprise Wiki Page (Content Types) -> Wiki Categories
- Click “Edit column”
- Change Column Term Set Setting select the term store you have created.
- Select okay