This document discusses data modulation and digital modulation. It defines data modulation as the process of converting analog signals to digital signals and vice versa, allowing computers to store and process analog signals. Digital modulation encodes a digital information signal into the amplitude, phase, or frequency of a transmitted signal. The types of digital modulation discussed are Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK). Examples of each type are provided.