The Service uses a feature of a user's browser to set a "cookie" on their computer. A cookie is a small data item that web sites can store on a computer in order to recognize the web browser uniquely, and by inference the user, during each visit.
The Service uses cookies to track information related to a user session. A user session is started and/or kept active each time a user accesses the website without an active user session and is kept active until they logout or are inactive for a set amount of time.
The Service can only read a cookie that the Service creates and sets on a user's computer. The Service cannot use cookies to read data off a user's hard disk other than the data contained within the cookie, or read cookie files not created by the Service. Users have the option with most browsers to turn cookies off if they should so desire, however due to the nature of the Service, turning cookies off may prevent the Service from functioning properly for that user.