The laser is a very powerful and very useful instrument in modern nanoscience and nanotechnology. The knowledge of the interaction mechanism of the laser beam with nanoparticles is needed to control the laser processing of different nano-objects. It was shown that the particle heating–melting–evaporation model can be successfully applied for many phenomena arising when colloidal nanoparticle interact with pulsed laser beams. The general approach of this model is discussed in detail. The two main components of the model, light absorption by particles, and the thermodynamics of phase transitions in particulate material are considered. Special attention is devoted to the correct estimation of the possible heat losses. The way in which the phase diagrams, where the different phase conditions of particle material are presented in laser fluence−particle diameter coordinates, were produced is demonstrated. It is shown how this model can be applied for understanding the mechanism of such complicated processes as particle-size reduction and submicrometer spherical particle growth, as well as other processes that occur when colloidal particles are irradiated by a pulsed laser.