PPI may refer to: Science and technology Biochemistry PPi, the anion P2O74−, a pyrophosphate Polyproline I helix, a type of polyproline helix Protein–protein interaction Medicine Patient package insert, a document to be provided to a patient providing details of their medication Patients and public involvement (PPI), a UK healthcare initiative Prepulse inhibition, of a later pulse Proton-pump inhibitor, of gastric acid secretion Psychopathic Personality Inventory, a personality test Psychophysiological Interaction, fMRI analysis technique Computing Parallel Peripheral Interface, of the Blackfin processor Programmable Peripheral Interface, Intel 8255 chip Programmable Peripheral Interconnect, an implementation of autonomous peripheral operations in microcontrollers Pixels per inch, number of pixels per inch in a display Other science and technology Pulsational pair-instability supernova Gabarit passe-partout international, in railways Picks per inch, a unit of textile measurement Plan position indicator, radar display Polypropylene polybenzyl isocyanate Business and organizations Italian People's Party (1919) (Partito Popolare Italiano), a Christian-democratic party Italian People's Party (1994) (Partito Popolare Italiano), a Christian-democratic party Peace Party of India, Uttar Pradesh Perusahaan Perdagangan Indonesia, Indonesian trading company Philips Phonographische Industries, later Philips Records Phonographic Performance Ireland, Irish music performance rights organisation Pirate Parties International, organisation for Pirate Parties Polly Peck International, UK company collapsed in 1991 Primarily Primates, primate sanctuary, Texas, US Productivity Products International, US software company later renamed Stepstone Progressive Policy Institute, a U.S. public policy think tank Pakistan Press International, a Pakistani news agency Other uses Pareto priority index, to prioritize projects Payment protection insurance Positive polarity item Producer price index a price index that measures the average changes in prices received by domestic producers for their output. Pre-purchase inspection Pulse polio immunization Port Pirie Airport, IATA airport code "PPI"