LifeLog aimed to compile a massive electronic database of every activity and relationship a person engages in. This was to include credit card purchases, web sites visited, the content of telephone calls and e-mails sent and received, scans of faxes and postal mail sent and received, instant messages sent and received, books and magazines read, television and radio selections, physical location recorded via wearable GPS sensors, biomedical data captured through wearable sensors. The high level goal of this data logging was to identify "preferences, plans, goals, and other markers of intentionality".^[2]

Another of DARPA's goals for LifeLog had a predictive function. It sought to “find meaningful patterns in the timeline, to infer the user’s routines, habits, and relationships with other people, organizations, places, and objects, and to exploit these patterns to ease its task" ^[2][3]

Generically, the term lifelog or flog is used to describe a storage system that can automatically and persistently record and archive some informational dimension of an object's (object lifelog) or user's (user lifelog) life experience in a particular data category.

News reports in the media described LifeLog as the "diary to end all diaries—a multimedia, digital record of everywhere you go and everything you see, hear, read, say and touch".^[4]

According to U.S. government officials, LifeLog is not connected with DARPA's Total Information Awareness.^[4]

The LifeLog program was canceled in January 2004 after criticism concerning the privacy implications of the system.^[5][6]