Abstract: Neuroinflammation, an intricate inflammatory process occurring in the central nervous system (CNS), plays an important role in host defense. Glial cells, including astrocytes and microglia, along with cytokines, chemokines, and the complement system are important components of neuroinflammation. A low level of neuroinflammation is associated with and contributes to various homeostatic and neuroprotective processes, such as removing pathogens or cellular debris and promoting tissue repair after brain injury. However, prolonged or maladaptive neuroinflammation has been implicated in neurodegenerative diseases, such as Alzheimer’s disease (AD), Parkinson’s disease, multiple sclerosis, and major depression. Increasing evidence indicates that targeting neuroinflammation may be a potential therapeutic intervention against neurodegeneration for delaying disease onset or progression. However, our current understanding of neuroinflammation remains limited.