Which brain network is most active when the mind is at rest and wandering?

The default mode network, often abbreviated DMN, is a set of brain regions that becomes especially active when a person is not focused on the outside world. It is linked to daydreaming, recalling the past, imagining the future, and thinking about oneself and others. The term became popular in the early 2000s, though researchers had noticed this resting-state pattern earlier. Key nodes include the medial prefrontal cortex, posterior cingulate cortex, and angular gyrus. Rather than being “idle,” the brain is doing internally directed work when the DMN is engaged.