This document discusses key concepts and terminologies related to parallel computing. It defines tasks, parallel tasks, serial and parallel execution. It also describes shared memory and distributed memory architectures as well as communications and synchronization between parallel tasks. Flynn's taxonomy is introduced which classifies parallel computers based on instruction and data streams as Single Instruction Single Data (SISD), Single Instruction Multiple Data (SIMD), Multiple Instruction Single Data (MISD), and Multiple Instruction Multiple Data (MIMD). Examples are provided for each classification.