Application Program Interface, a defined set of routines and protocols for building application software.
An instruction set architecture (ISA) is an abstract model of a computer. It is also referred to as architecture or computer architecture.
RISC-V is a free and open ISA enabling a new era of processor innovation through open standard collaboration. Born in academia and research, RISC-V ISA delivers a new level of free, extensible software and hardware freedom on architecture, paving the way for the next 50 years of computing design and innovation.