Vipassana, meaning 'to see things as they really are,' is one of the oldest forms of meditation in the Buddhist tradition. It involves observing bodily sensations, thoughts, and emotions with precise, impartial attention — noticing their arising, duration, and passing without clinging or aversion. The most widespread modern form was taught by S.N. Goenka, who offered free 10-day silent retreats worldwide that have now been attended by millions of people. Vipassana's core insight is that all physical and mental phenomena are impermanent, and that suffering arises from our habitual reactions to them.

Reference:

Wikipedia: Vipassana

https://en.wikipedia.org/wiki/Vipassana