Businesses spend a lot of effort and expense setting up their networks to provide all the data flows and applications necessary so that their employees are very productive in performing their tasks.
These networks are vital assets to the business and require absolute protection against unauthorized access, malicious programs, and degradation of performance of the network. It is no longer enough to only use Anti-Virus applications.
By the time malware is detected and those signatures added to the antiviral definitions, access is obtained and havoc wreaked or the malware is buried itself inside the network and is obtaining data and passwords for later exploitation.
An article by Drew Robb in eSecurity Planet on September 3, 2015 (http://www.esecurityplanet.com/network-security/advanced-threat-detection-buying-guide-1.html) cited the Verizon 2015 Data Breach Investigations Report where 70 respondents reported over 80,000 security incidents which led to more than 2000 serious breaches in one year.