Dynamic light scattering (DLS) has evolved as a fast, convenient tool for particle size analysis of noninteracting spherical colloids. In this historical review, we discuss the basic principle, data analysis, and important precautions to be taken while analyzing colloids using DLS. The effect of particle interaction, polydispersity, anisotropy, light absorption, and so forth, on measured diffusion coefficient is discussed. New developments in this area such as diffusing wave spectroscopy, particle tracking analysis, microrheological studies using DLS, and so forth, are discussed in a manner that can be understood by a beginner.