This lecture covers the fundamentals of quantum memories, including photon echoes, atomic frequency comb (AFC) quantum memory, and time multiplexing. It explores the coherent light-matter interactions, Bloch sphere, and inhomogeneous dephasing. The instructor discusses the challenges and solutions in achieving linear storage processes and the complex optical setups required for optical data storage. Additionally, the lecture delves into storing optical photons as spin excitations and the AFC spin-wave memory in 151Eu3+:Y Sio. The AFC echo control of dephasing and experimental setups for quantum memories are also presented.