Parallella is a single-board computer roughly the size of a credit card or Raspberry Pi. Parallella runs Linux. It has 18 cores (2 ARM, 16 RISC) and you can buy it online for about $150. This talk will explore two questions: (1) How parallel execution differs from serial, and (2) Why we care about parallelism. This talk is the sequel to Ray's Parallella talk from 2015. To get a head-start on the subject, check out Part One: http://rayhightower.com/blog/2015/08/22/madison-ruby-and-parallella/.