If you only read the Documentation wiki, no more information is collected than is typically collected in server logs by web sites in general. The website uses Google Analytics to gather anonymous usage statistics in order to allow us to track use of the site and continuously improve the browsing experience for your benefit. No personal data is gathered, beyond data voluntarily entered when filling out forms or ordering products.
If you contribute to the Documentation wiki, you are publishing every word you post publicly, and your words will be associated with your wiki user name. If you write something, assume that it will be retained forever.
Publishing on the wiki and public data
Simply visiting the web site does not expose your identity publicly. When you edit any page in the wiki, however, you are publishing a document. This is a public act, and you are identified publicly with that edit as its author.
To publish a page in the wiki, you need to be logged in and you will be identified by your username. For many customers, this username is your email address.
Every time you visit a web page, you send a lot of information to the web server. Most web servers routinely maintain access logs with a portion of this information, which can be used to get an overall picture of what pages are popular, what other sites link to this one, and what web browsers people are using. It is not the intention to use this information to keep track of legitimate users.
Sharing information with third parties
All text added to this wiki is available for reuse subject to the Submissions Policy.
Data on users, such as the times at which they edited and the number of edits they have made are publicly available via "user contributions" lists, and in aggregated forms published by other users.
Removal of user accounts
Once created, user accounts will not be removed. It may be possible for a username to be changed (depending on the number of edits you have).
Deletion of content
Removing text does not permanently delete it. In normal articles, anyone can look at a previous version and see what was there. If an article is "deleted", any Sysop can see what was deleted.