[xwiki-users] How to use feature like watch space and document index?

As i enter to main space after login, i see these kind of options like watch wiki,document index,watch space. What is is the user of these features. As name * watch wiki or watch space* suggests, looks like whenever there is a modification/addition on on wiki, it will send the mail to user email id registered on xwiki. *Is that correct?* *What about document index? feature?* *Another issue i am facing is* For my user i have denied the the view permission on invitation space. But still i am able to see that ivitation space on main space webhome page? i dont give my user the feature to send invitation to others Thanks