Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Valve Anti-Cheat, abbreviated to VAC, is an anti-cheat solution developed by Valve Corporation as a component of the Steam platform. VAC was first released with Counter-Strike 1.4 in 2002, following Valve''s decision to forego PunkBuster in preference of a proprietary system. The initial version, VAC1, saw success for a period, but in March or April 2004 updates ran dry as the Valve engineers maintaining it moved on to the production of its successor, VAC2. VAC1 swiftly became virtually useless during this period of development, but since its June 20, 2005, launch VAC2 has successfully overseen a decline in the number of cheating players across games protected by it.