Vipassana is a Pali word that means: "seeing clearly", "seeing specially", or "seeing through" (Vi = clearly, specially, into, through + passana = seeing).
Vipassana means introspection, intuitive wisdom, and intuitive knowledge. Vipassana is often translated as Insight. Seeing what clearly? Insight into what? Vipassana means seeing through the true nature of reality or Insight into the true nature of reality. Vipassana is the direct and intuitive understanding of the true nature of all mental and physical phenomena. Vipassana is based on the Four Satipatthanas, the Four Foundations of Mindfulness. Thus, insight is achieved through the consistent and gradual application of the Four Foundations of Mindfulness. Insight develops through the gradual application of the Four Foundations of Mindfulness:
Mindfulness of the body
Mindfulness of feelings
Mindfulness of the mind
Mindfulness of mind objects
Excerpt from the book "The Only Way" by The Late Most Venerable Ajarn Tong Sirimangalo, translated by Kathryn Chindaporn and published in Chomtong, Chiang Mai, Thailand, 1999