A set of areas of the brain known to be involved in olfaction, memory and in regulating emotions. The limbic system is known to influence the endocrine system (organs which secrete hormones).
All of the areas that compose it are located towards the base of the brain around the thalamus: septum, fornix, hippocampus, amygdala, and the insular and posterior fronto-orbital cortex. Some add the hypothalamus to this.
The limbic system is composed of white matter (formed from axons arising from the cell bodies of neurones that form the grey matter).