This document compares analog and digital signals. It discusses that analog signals are continuous signals representing physical measurements, denoted by sine waves, and examples include temperature sensors and light sensors. Digital signals use discrete 0s and 1s to represent information, are denoted by square waves, and examples include computers and CDs/DVDs. The document provides details on the differences between analog and digital signals in terms of bandwidth, noise immunity, flexibility, applications, processing, and measurement errors.