SPI explained

SPI may refer to:

Businesses

Simulations Publications, Inc., a former US board game publisher
Sony Pictures Imageworks, a subsidiary of Sony specializing in computer animation
Stream Processors, Inc, a semiconductor company

Indian Protection Service, a former Brazilian agency whose Portuguese name (Brazil's native language) is Serviço de Proteção ao Índio
Sisters of Perpetual Indulgence, an LGBT activism movement
Society for Philosophical Inquiry
Society of the Plastics Industry, a U.S. trade association
Software in the Public Interest
Software Patent Institute, US
St. Pascual Institution, Philippines school
St. Paul's Institution, a school in Malaysia
Sustainable Preservation Initiative, of cultural heritage
Sveriges Pensionärers Intresseparti, or Swedish Senior Citizen Interest Party
Social Progress Imperative, a US-based nonprofit created in 2012

SCSI Parallel Interface
Serial Peripheral Interface, the de facto standard for serial communication
Security Parameter Index in IPSec tunneling
Server Programming Interface, an API for PostgreSQL to run SQL queries from the C programming language
Service provider interface, an API for Java
Software Process Improvement, an approach to software development initiated by the Data & Analysis Center for Software
System Packet Interface for networking
Stateful Packet Inspection for networking

Schedule Performance Index, a figure of merit used in earned value management
Single-point injection
Social Progress Index of countries
Abraham Lincoln Capital Airport (IATA code), US
Sediment Profile Imagery underwater
South Padre Island, a resort town in Cameron County, Texas
Spi-calculus (Synchronous -calculus), a proposed extension of -calculus
Superintendent of Public Instruction, a state-level official in the United States who is responsible for public education (all states have such an official, but some states have a slightly different title for the position)
Swiss Performance Index, one of the indecies used to measure the performance of the SIX Swiss Exchange