Recently, much attention has been drawn to unraveling the mechanisms of neurodegenerative and neuroinflammatory disease pathogenesis. A special role in the development of neuropathologies is assigned to the interaction of the nervous and the immune systems. Microglia are the cells of the immune system that function as resident macrophages of the central nervous system (CNS) and are involved in the development of CNS, as well as in homeostatic interactions. Impaired microglia can contribute to neuroinflammation and neurodegeneration. With the help of genome editing technologies, the main paradigms in the development and functions of microglia have been addressed. At the same time, an understanding of the mechanisms of regulation of microglia in normal and pathological conditions is necessary to create an effective therapy aimed at treating various neurological diseases. This review focuses on recent findings on the origin of microglia, its regulatory role in the central nervous system, as well as its contribution to the development of neuroinflammation.