Non-Session Data is information that cannot be gleaned from a user by their usage of a site. This should mean that the data is unobtainable to the site, but through a combination of informed guesswork and cookies, many analytics programs can still provide this data to sites.
There are also many companies that can take your data and match it up to user records, although the legality of this varies from place to place so it is not recommended.
Glossary Index