Research: What are the Gnostics?

During the show Gospel of Judas they made mention of the word "gnostics" alot.
Here's what it means:

Christian and non-Christian groups of the second and third centuries. Although there were many types, they all seemed to think that the individual can obtain spiritual liberation from the bodily world of ignorance and illusion through gnosis or insight and identification with the divine. Their ideas challenged the unity of the church because they denied the goodness of creation and the humanity of Jesus Christ.
gbgm-umc.org/umw/corinthians/glossary.stm

comes from Greek "gnosis" meaning "knowledge of God".
anomalous-images.com/text/appb.htm

Gnosticism is a blanket term for various mostly mystical religions and sects most prominent in the first few centuries A.D.
en.wikipedia.org/wiki/Gnostics