reality is made of sensations
Sensations
Insight meditation is the study of sensations in order to understand our perception of reality. Sensations are what we perceive through our six sense-doors (five senses and thoughts). They are not to be confused with impressions or emotions. Sensations give rise to them. It is their root. That is why if we can understand sensations, we can understand everything we are capable of knowing.
The Insight practice explained here is called noting and was developed by Mahasi Sayadaw. It consists of noting our sensations and giving it a category without judging them.