The aim of the discussion is to explain the evolution of galaxies from the blue cloud via the green valley to the red sequence throughout their lives. It is well established that the regulation in star formation in galaxies is the main key which derives galaxies from the blue cloud to the red sequence. In this respect, there are many mechanisms such as AGN feedback, strangulation process and other gas removal processes including ram pressure gas stripping and galaxy-galaxy interaction/merger, which regulate the star formation in galaxies and derive them towards the red sequence. The discussion will shed light on these mechanisms and their roles to explain the galaxy evolution.