Different from online behavior, the idea of an online footprint regards the lasting trace that remains of the entity’s original behavior. The entity can be an individual, organization, or even country. The footprint can be a by-product of the entity’s behaviors, or its purpose. An online footprint may be specific to an individual and reveal -- or narrow down -- his/her identity, in which case the footprint also serves as an identifying signature. 

What constitutes a person’s signature?  Even within a single platform, people relish creating multiple identities. Non-human agents further cloud the picture. Sockpuppet accounts are used for manipulation of opinions and commercial purposes, and cyborg as well as bot accounts flourish, creating an online mish-mash of identities and behaviors. Here, we research online human footprint and extract knowledge from user-generated content.