International law is defined traditionally as the rules determining conduct between states, but increasingly also applies to individuals and corporations. It consists of both explicit agreements between states in treaties and conventions, as well as customary law developed from widespread and consistent state practice. Key areas of international law include diplomacy, war, human rights, and the environment. War and human rights are particularly controversial as they can infringe on national sovereignty but many agreements and conventions have been put in place to define acceptable and prohibited conduct in these areas.