Resistance to HIV refers to an active response on the part of individuals, households, communities that is aimed at avoiding or minimizing exposure to the virus. To understand resistance to HIV it is necessary to first identify factors and processes that underlie individual susceptibility to HIV infection. Susceptibility is the chance of an individual becoming infected with HIV, which is directly related to her or his chance of exposure, the risk environment they confront, and the riskiness of their behaviors. Strategies that actively bolster resistance should decrease individual susceptibility through such actions as behavior change and/or the modification of environmental risk conditions faced by individuals.