Organizations that need to protect sensitive information assets -- in order to comply with corporate or regulatory policies, protect competitive advantage, or simply enable new business processes -- have come to recognize Host Intrusion Prevention (HIP) as a critical component of a defense in-depth security strategy. While the need for this last layer of defense is widely understood, there remains considerable confusion over what constitutes an effective HIP product. There are many HIP technologies that offer some value, but do not go far enough in solving the overall problem. HIP solutions need to embody the following characteristics, or be relegated to the shelf as impractical. They must provide comprehensive protection, have minimal performance impact on the host, be extremely robust and reliable, and offer low cost of ownership. This white paper explains what to look for in HIP products, and introduces the concept of "Deep HIP" as a means of characterizing effective solutions in this area.