Left: Hindu symbol of the Muladhara Chakra , as depicted by Swami Satyananda Saraswati. [Source: "Theories of the Chakras" by H. Motoyama, p232)

Description by various yoga texts:

Shat-chakra-nirupana - By meditating on Pard (or Kundalinī) who shines within the Mūla Chakra, with the luster of ten million suns, a man becomes Lord of speech, King among men, and an Adept in all kinds of learning.  He becomes ever free from all diseases, and his inmost spirit becomes full of great gladness.  Pure of disposition by his deep and musical words, he serves the foremost of the Devas.

Gorakshashtakam description – The first Chakra called, ādhāra (Mūlādhāra) is like burnished gold; meditating (on it) with the gaze fixed on the tip of the nose, one is freed from sin. [Verse 78].  

Also known as: Sacral, Security Center

Location: The perineum (base of spine), the point between the anus and the sex organs (the Coccyx area)

Color : Red

Symbol & Element: Earth; Square

Physical Areas: Reproductive system; tailbone; legs and feet

Astrology sign: Fire Signs of Aries, Leo and Sagittarius

Physiology affected by Chakra: Lymph system, skeleton system (teeth and bones), kidney, immune system, the prostate gland in men, the sacral plexus, the bladder and elimination system, and the lower extremities (legs - feet, ankles , etc.). Also the nose, since it is the organ of the sense of smell, and associated with survival

Endocrine gland: Adrenal glands

Sense: Smell

Conscious Development Aspect: Primarily associated with stabilising our physical existence.  Through this Chakra it is said we rid ourselves of insecurity and therefore develop confidence and security of mind.  This stability lays the foundations for our progression to a higher level of being.  Feelings of insecurity are believed to be the result of an under active root Chakra, whereas an over active one leads to arrogance resulting in greed and a preoccupation in materiality.

UMO Perspective: Personally we can understand why the first Chakra would be concerned with security issues, after all, the first steps in developing maturity of mind can only begin once we become secure within ourselves.  Until we can develop an inner-strength we will always be preoccupied with petty disputes as we lash out at what we perceive to be an unjust and cruel world.  Of course that is not to say that our world is not full of injustice, but how we cope with this will directly influence our future prosperity.  Before we can make a positive impact on life we need to become part of the solution instead of being part of the problem, and to do this means we must recognise that despite life's injustices, such things can only be overturned with positive actions, and this means releasing ourselves with a preoccupation with our self.  Self centred people tend to be steeped in insecurity issues.  They feel constantly victimised and as such the slightest event can send them into an outrage.  For such people, attacks can seem the best form of defence and as such they end up becoming angry, unsociable and vindictive. In short, they become the very type of person that contributed to their own insecurity in the fist place.   They become part of the problem.

Left: The Muladhara is located at the base of the spine and is associated with the colour Red.
 

Left: C.W. Leadbeater's pictorial description of the Root Chakra (Muladhara). [Source: "The Chakras" by C.W.Leadfbeater].