A somewhat tongue-in-cheek summary of the three marks of existence is as follows:
Everything changes (anicca).
That is not satisfying (dukkha).
It's nothing personal (anatta).
Anicca is usually translated as impermanence and refers to the fact that everything is constantly changing. Everything that comes to be passes away.
Dukkha is a linked characteristic in that this impermanence is experienced as unsatisfactory or as suffering. There is clearly much about life that is unsatisfactory. Humans experience old age, sickness and death, for instance. However, it is not that that there is nothing in this world that brings us happiness, but this happiness we experience has no permanence; it does not last. Inherent in this happiness is the inevitability of it ending, and it is this which makes it unsatisfactory. However, it is debatable whether impermanence is inherently unsatisfactory or just that we experience it as such as a result of craving and clinging.
Anatta refers to the impersonal, the non-self aspect of existence. There is no enduring essence of anything in this world including the self. We can see ourselves as being the same over time, but this is actually just an appearance of continuity not evidence of an enduring essence that is actually the same. There is no "I" beyond this continuity, no soul or ego. This non-self characteristic extends not just to the self but to all things.
Insight wisdom (vipassana panna) consists "just of this experience of the three characteristics applied to one's own bodily and mental processes, and deepened and matured in meditation" (Nyanaponika, 2013).
It is this insight wisdom and what leads up to it that I would like to explore in future posts.