Glial cells are support cells for the nervous system. In Greek, Glia means "glue". Glia are said to be the glue of the nervous system. Glia occur in both grey matter and white matter.

Glia are thought to have four main functions:

  1. To surround neurons and hold them in place,
  2. To supply nutrients and oxygen to neurons,
  3. To insulate one neuron from another,
  4. To destroy pathogens and remove dead neurons.

Glia may have more functions than just these four.