This document provides an introduction to parallel computers. It discusses how parallel computers can be classified based on their machine structure and how parallel operations can be grouped by abstraction level or argument type. Parallel programming is necessary for tasks like modeling complex systems in various scientific domains like physics, biology, and weather. It also discusses concepts like speedup, efficiency, and different types of parallel computers and processing methods. Figures and tables are included to illustrate concepts like the von Neumann model versus the human brain in processing information.