This IDC presentation was presented on June 12, 2008, at the "IT Security — Unlocking the Opportunities" briefing in London. The presentation looks at the UTM appliance market in Western Europe from a historical point of view and shows how and why unified threat management is now the largest segment share by revenue in the total security appliance market in Western Europe. The data and information presented in this research was the result of detailed interviews conducted with security appliance vendors tracked in IDC's Security Appliance tracker.