Nama and rupa
All phenomena in and around ourselves are only nama and rupa which arise and fall away; they are impermanent. Nama and rupa are absolute realities, in Pali: paramattha dhammas. We can experience their characteristics when they appear, no matter how we name them. Those who have developed ' insight' can experience them as they really are: impermanent and not self. The more we know different namas and rupas by experiencing their characteristics, the more we will see that 'self' is only a concept; it is not a paramattha dhamma.
Nama and rupa are different types of realities. If we do not distinguish them from each other and learn the characteristic of each we will continue to take them for self. For example, hearing is nama; it has no form or shape. Hearing is different from ear-sense, but it has ear-sense as a necessary condition. The nama which hears experiences sound. Ear-sense and sound are rupas, which do not experience anything; they are entirely different from the nama which hears. If we do not learn that hearing, ear-sense and sound are realities which a re altogether different from each other, we will continue to think that it is self which hears.