HPA

HPA may refer to:

Finance

 * Home Price Appreciation, the change in value of a single-family home, calculated using the United States Office of Federal Housing Enterprise Oversight's House Price Index

Organizations

 * Halifax Port Authority, a port authority operating as a not-for-profit Crown corporation of the Government of Canada
 * Health Protection Agency, an independent health organization in the United Kingdom responsible for protecting the population from hazards such as radiation, chemicals, poisons and infectious diseases
 * Hurlingham Polo Association, the governing body for polo in the UK

Measurement unit

 * Hectopascal (hPa), a unit used worldwide for air pressure

Science

 * Hypothalamic-pituitary-adrenal axis (physiology), how the hypothalamus, pituitary and adrenal glands work together to regulate hormone levels and maintain homeostasis
 * Human physical appearance (anthropology)
 * Human platelet antigens (Clinical Medicine, Blood transfusion, alloantigens)

Technology

 * High Performance Addressing, an LCD display technology, a passive-matrix display technology which provides better response rates and contrast than traditional LCD displays. They aren't as crisp or fast as active-matrix (TFT) displays, however they're a lot cheaper to produce. HPA was used some years ago in entry level notebooks, but now it's practically disappeared as TFTs are less expensive
 * High Power Amplifier (satellite dish), used in two-way satellite internet (this is the transceiver part)
 * Host Protected Area, a reserved area on the data storage that is outside file system of the operating system running. Such area is hidden from the operating system and the file system, and it is normally unable to view the content except with special tools
 * Human-powered aircraft (human powered transport)
 * High Pressure Air (paintball/airsoft) is used as a source of propulsion in the sport paintball and in custom gas airsoft guns.

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