The Atharva Veda is the last of the Vedas. It has not always been accepted as a Veda, which are often spoken of as three. It still contains many hymns from the Rig Veda but also has some more popular magic spells which are outside of the strictly ritual-knowledge orientation of the other Vedas.
Like the Rig Veda it is a collection of hymns but of a more diverse character, some very exalted like the Rig Veda others of more common nature. As such it gives us a better idea of the life of common people in Vedic times.
Though the classical Atharva Veda is related to religious and socio-cultural aspects of the society, it dwells on an entirely different level of knowledge. The hymns that are contained in Atharvaveda are more diverse in nature and character than the ones in Rig Veda. It is also of a much simpler language than the Rig Veda. Most scholars in fact don't even consider Atharva Veda to be a part of the Vedas.
The Atharva Veda basically consists of charms and spells that were prevalent at that time in the society. The Atharva Veda presents a portrait of the Vedic society. One can find an independent and parallel stream of knowledge and thought in the Atharva Veda. It is said that the mantras are very powerful and should be chanted with much caution and only by specific priests who have a wide knowledge about the Atharva Veda.
The Atharvaveda is associated with the area and cult of mystic science and the dark side of science. It is said to deal with death, spirits and afterlife. It is said that if pregnant women attend the rituals where Atharva Veda is chanted, the effects can be so powerful that they may suffer an abortion. An example of the power of Atharva Veda is sited in epic of Mahabharata. When the Pandavas are exiled for a period of thirteen years, they consult Atharva Veda and shrink time so that it compresses to thirteen days.