RED relates to the BASE chakra situated at the base of the spine
The organs to which this chakra relates are the kidneys and bladder .(The kidneys are formed within the pelvis and here they link with the base chakra energy, although prior to birth they rise to the position in the loins with which we are more familiar). The vertebral column, hips and legs are also areas related to this chakra. The endocrine gland to which this colour relates is the adrenal gland.
On the psycho-spiritual level, this chakra relates to self awareness. That is to say our awareness of ourselves as human beings and our place on earth. It is the area of survival and relates to our basic human instincts of fight or flight. Red gives us courage and strength. The colour relates to stability and security.