Three basic gunas, satwa, rajas and tamas (Triguna) are due to the nature that bind the perishable bodies with the imperishable soul.
There, Satwa is virtuous, pure and stainless pure (presumptions and prejudices) enlightened by knowledge (of doable and non-doable), binds people to happiness and knowledge.
Satwa is virtuosity, purity, knowledge, intellect and simplicity. It is free from biases, presumptions and prejudices. Satwa is knowledge that enlightens people of doable and non-doable (not worth doing) and frees them from disgrace and sin.
Rajas is (excitement, passion and administration). It imbues impulse and passion and creates thirst for power, pleasure and passion in people. It binds those in bodies to their fruit-bearing actions and emotions.
Ego, attachments and selfishness are key impurities due to rajas effects, but it may convert to tamas as well.
Let it be known, that Tamas, the darkness is born of ignorance (or indoctrinated knowledge), that enchants all bodied beings and binds them to insanity, (due to ill logic and indoctrinated knowledge), indolence and slumber, O Bharat!
Tamas is inertia, darkness, ignorance and devilish. Tamas literally means darkness that is born of ignorance (opposite of knowledge that leads to enlightenment). Tamas deludes people out of incorrect, distorted and eccentric knowledge. Indoctrination of people by criminals or terrorists is due to tamas and it binds people to insanity. Carelessness, callousness, selfishness and greed are other forms of Tamas, which arise from some kind of ignorance and darkness.