Data Loss Prevention (DLP) is a computer security term referring to systems that identify, monitor, and protect data in use, in motion and at rest
From Wikipedia: http://en.wikipedia.org/wiki/Data_loss_prevention_software
Data Loss Prevention (DLP) is a computer security term referring to systems that identify, monitor, and protect data in use (e.g., endpoint actions), data in motion (e.g., network actions), and data at rest (e.g., data storage) through deep content inspection, contextual security analysis of transaction (attributes of originator, data object, medium, timing, recipient/destination, etc.), and with a centralized management framework.