"Precarity is a word that is coming to be used by more and more people to designate what they take to be key continuities in the conditions, experiences, and implications of a growing majority of the human population to the characteristic mode of exploitation in the contemporary world.
More specifically, precarity in these discourses indicates an ongoing casualization of the terms of employment under which ever more people labor to survive in today's world, usually conjoined to an ongoing informalization of the terms under which ever more people struggle to secure the basic conditions of housing, healthcare, access to knowledge, and legitimate legal recourse under which they live.
Whether it denotes the dismantlement of established entitlements in relatively democratic North Atlantic societies arising out of the market fundamentalist gospel of an endlessly elaborated and augmented "personal responsibility," or denotes the erection of barriers to the achievement of entitlements for people in the overexploited regions of the so-called "developing world" through the terms of globalization euphemized as "free trade," precarization describes a social and cultural inculcation of human insecurity as well as the consequent opportunistic mobilization of that insecurity to maintain and consolidate the complicity, obedience, or at any rate the acquiescence, of the overabundant majority of people on earth to the terms of their own exploitation and to the disproportionate benefit of incumbent elites.
"Casualization" is a term that describes the emerging preponderance of people who labor in temporary, part-time, intermittent, "flexible" forms of employment, typically with diminished entitlements, security, occasions for advancement or provision for the future, or institutional recourse in matters of grievance. Usually this tendency is described as a shift away from the expectations of especially the citizens in relatively democratic North Atlantic societies that desirable employment will be permanent or at any rate stable, full-time, skilled, characterized by relatively secure benefits, pensions, underwritten in some cases by professional traditions like tenure but more broadly by the provision of more or less extensive welfare entitlements.
"Informalization" is a term that is often used interchangeably with casualization to describe the same trends in prevailing conditions of employment, but also describes the contemporary proliferation of insecure, "unconventional" (though ever more conventional) "off the books" social transactions more broadly: bribery, black-markets, influence peddling, kickbacks, barter, payment in kind, blackmail, unpaid labor, squatting, peer-to-peer production, and so on." (http://amormundi.blogspot.com/2007/02/precarity-and-experimental-subjection.html)