Chapter 7 Firewall for FortiOS 5.0 : Firewall objects : Security profiles : Data Leak Prevention (DLP)
  
Data Leak Prevention (DLP)
Data Leak Prevention is used to prevent sensitive information from leaving your network. When people think of security in the cyber-world one of the most common images is that of a hacker penetrating your network and making off with your sensitive information, but the other way that you can lose sensitive data is if someone already on the inside of your network sends it out. This does not have to be an act of industrial espionage. It can just be a case of not knowing the policies of the organization or a lack of knowledge of security or laws concerning privacy.
For instance, a company may have a policy that they will not reveal anyone’s Social Security number, but an employee emails a number of documents to another company that included a lengthy document that has a Social Security number buried deep within it. There is not malicious intent but if the information got out there could be repercussions.
If an organization has any information in a digital format that it cannot afford for financial or legal reasons, to leave its network, it makes sense to have Data Leak Prevention in place as an additional layer of protection.