Impermanence (Pāli: anicca) expresses the Buddhist notion that all compounded or conditioned phenomena (all things and experiences) are inconstant, unsteady, and impermanent. Everything we can experience through our senses is made up of parts, and its existence is dependent on external conditions. Everything is in constant flux, and so conditions and the thing itself are constantly changing. Things are constantly coming into being, and ceasing to be. Since nothing lasts, there is no inherent or fixed nature to any object or experience. According to the doctrine of impermanence, life embodies this flux in the aging process, the cycle of rebirth (saṃsāra), and in any experience of loss. The doctrine asserts that because things are impermanent, attachment to them is futile and leads to suffering (dukkha).
Why is attachment to things futile?
because things are impermanent