philosophy
What are the three gunas?
What the tradition says
In Hindu thought the three gunas are sattva, rajas, and tamas. The word guna means a quality or strand. The tradition holds that these three qualities run through all of nature and mix together in different amounts. Sattva is linked to clarity, calm, balance, and light. Rajas is linked to energy, motion, drive, and restlessness. Tamas is linked to heaviness, rest, dullness, and inertia. None is seen as standing alone. Everything is said to hold all three, with one or another more present at a given time.
Where the idea comes from
The three gunas are a key part of Samkhya, one of the old systems of Indian thought. The Gita also speaks of them at length. There they are used to describe nature, and to sort temperaments, actions, and even food into sattvic, rajasic, and tamasic types. Over time the idea spread widely and shaped how many people talk about mood, character, and balance in daily life.
How people use the idea
In everyday talk, people use the gunas as a simple way to describe states of mind. A quiet, focused mood may be called sattvic. A busy, driven mood may be called rajasic. A tired, heavy mood may be called tamasic. Food is sometimes sorted the same way, with fresh and light food called sattvic and heavy or stale food called tamasic. This is a way of thinking within the tradition, not a measured fact. People hold it differently across regions and schools.