This document summarizes key concepts about waves and signals from Chapter 2. It discusses the properties of waves including amplitude, period, frequency, wavelength, and phase. It also covers electromagnetic energy, propagation of electromagnetic waves, and transmission impairments like attenuation and distortion. The document defines data and signals, describing electrical, light, and electromagnetic signals. It compares analog and digital signals, explaining how analog signals have an infinite range of values while digital signals have a limited set. Finally, it discusses data rate limits and compares the impact of noise, information loss, and errors on analog versus digital signals.