The limbic system (or Paleomammalian brain) is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and the sense of smell. 

The term "limbic" comes from the Latin limbus, for "border" or "edge".

Some scientists have suggested that the concept of the limbic system should be abandoned as obsolete, as it is grounded more in transient tradition than in facts.

 In recent years, it’s become clear that the unconscious brain is able to process vast amounts of information in parallel, thus allowing it to analyze large data sets without getting overwhelmed. Human reason, in contrast, has a very strict bottleneck and can only process about four bits of data at any given moment. But this raises the obvious question: how do we gain access to all this analysis, which by definition is taking place outside of conscious awareness?

As Michel Tuan Pham (Columbia University) puts it, emotions are like a “privileged window” into the subterranean mind.

Comment: The limbic system (emotions) is the decision weighting system that is tied to subconcious processes.