The document discusses simple harmonic motion (SHM), where a particle moves back and forth such that its acceleration is directly proportional to its distance from a fixed point. SHM has the properties that the particle's velocity is zero at the amplitude of its oscillation, and it travels between the points of -a and +a on its axis. Examples are given of particles moving according to SHM equations, and exercises are provided to practice determining SHM, periods of motion, and maximum values.