There are six limbs of the Vedas, known as VedAngas. They symbolically represent the organs of the Veda Purusha.
1. SikshA -- Nose
2. Chandas -- Feet
3.VyAkaraNa -- Mouth
4. Nirukta -- Ears
5. Jyotisha -- Eyes
6.Kalpa -- Arms
SikshA is the science which deals with articulation and pronunciation.
Chandas is the science of metrics. It deals with Vedic metres.
VyAkaraNa is the science of grammar.
Nirukta is the science which deals with the etymological interpretation of words.
Jyotisha is the science of astronomy. It is primarily oriented towards determining the most appropriate time for performance of Vedic sacrifices and rituals.
Kalpa is the science which deals with rituals and prescribes rituals for sacrificial acts.
The Srauta sUtras contain a detailed description of sacrifices.
The Grihya SUtras prescribe rules for conducting various ceremonies pertaining to domestic life.
The Dharma SUtras consist of laws governing religious ways of life and secular matters as well.
The Sulva sUtras deal with the architecture of sacrificial altars for undertaking different kinds of sacrifices.
The VedAngas greatly help us in proper understanding and application of the Vedas. In case there is a difference between the two, Vedas will always prevail over the VedAngas . Thus Sruti PramANam is the most authentic pramANa.