This document is an active learning assignment on OFDM (Orthogonal Frequency Division Multiplexing) prepared by Keerthana Nambiar for the subject of Digital Communication under the guidance of Prof. Chintan Patel at Gandhinagar Institute of Technology. It discusses why OFDM is used by explaining how its orthogonal subcarriers eliminate cross-talk. The principles and block diagram of OFDM are presented, along with its advantages like immunity to fading, resilience to interference, and simpler equalization. Disadvantages around high peak-to-average power ratios and sensitivity to carrier offsets are also noted. Applications of OFDM include digital audio/video broadcasting, wireless LAN, WiMAX, Li-Fi, LTE