Tools for studying human microglia: In vitro and in vivo strategies

•Microglia are dependent on their environment for aspects of their cellular identity.•Stem cell derived microglia offer strategic advantages over other culture methods.•Genetic editing and patient-derived lines permit exploration of disease states.•Coculture methods can dissect microglia interactions with other CNS cell types.•Xenotransplantation can restore environment-dependent microglia identity.