A system for determining an interest of a user based on usage data is provided. Usage data corresponding to a plurality of websites accessed by a user is received from one or more computing devices of the user. The received usage data is categorized into a plurality of categories based on character strings that reference the individual websites. What content items from individual websites the user has selected to view is recorded in order to identify one or more items of interest. An activity of the user at a given time period is predicted based on the categorizations, the identified one or more items of interest, and times and duration of times the user viewed the individual websites. The system performs an action at the given time period based on the predicted activity.