Skandhas (Sanskrit) or khandhās (Pāḷi) means "heaps, aggregates, collections, groupings".It refers to the five aggregates of clinging (Pañcupādānakkhandhā), the five material and mental factors that take part in the rise of craving and clinging. They are also explained as the five factors that constitute and explain a sentient being’s person and personality.
The five aggregates MN 109 MN 143 SN 22:48 SN 22:79 SN 22:100 or heaps are: form (or material image, impression) (rupa), sensations (or feelings, received from form) (vedana), perceptions (samjna), mental activity or formations (sankhara), and consciousness (vijnana).
Suffering arises when one identifies with or clings to the aggregates. This suffering is extinguished by relinquishing attachments to aggregates. The nature of all aggregates is intrinsically empty of independent existence.
The Buddha teaches in the Pali Canon the five aggregates SN 22 as follows:
"Form" MN 28 or "Matter" (Skt., Pāli रूप rūpa; Tib. gzugs): matter, body or "material form" of a being or any existence. Buddhist texts state rupa of any person, sentient being and object to be composed of four basic elements or forces: earth (solidity), water (cohesion), fire (heat) and wind (motion)
"Sensation" or "Feeling" MN 44 SN 22:57 (Skt., Pāli वेदना vedanā; Tib. tshor-ba): sensory experience of an object. It is either pleasant, unpleasant or neutral.
"Perception" SN 22:57 (Skt. संज्ञा saṃjñā, Pāli सञ्ञा saññā, Tib. 'du-shes): sensory and mental process that registers, recognizes and labels (for instance, the shape of a tree, color green, emotion of fear).
"Mental Formations" or "Fabrications" DN 33 MN 44 SN 22:57 (Skt. संस्कार saṃskāra, Pāli सङ्खार saṅkhāra, Tib. 'du-byed): "constructing activities", "conditioned things", "volition", "karmic activities"; all types of mental imprints and conditioning triggered by an object. Includes any process that makes a person initiate action or act.
"Consciousness" SN 22:57 (Skt. विज्ञान vijñāna, Pāli विञ्ञाण viññāṇa, Tib. rnam-par-shes-pa): "discrimination" or "discernment". Awareness of an object and discrimination of its components and aspects, and is of six types.
The five skandhas give rise to a sense of personality, but are dukkha, impermanent, and without an enduring self MN 11 MN 144 SN 22:22 SN 22:59 SN 22:85 or essence. Each aggregate is an object of grasping (clinging), at the root of self-identification as "I, me, myself". Realizing the real nature of kandhas, both in terms of impermanence and non-self, is necessary for nirvana. This 'emptiness from personality' can be found in descriptions of the enlightened, perfected state of Arhat and Tathagata, where there is no longer any identification with the five kandhas.
Eighteen Dhātus and Four Paramatthas
The eighteen dhātus – Six External Bases, Six Internal Bases, and Six Consciousnesses – function through the five aggregates. These dhātus MN 148 SN 14 can be arranged into six triads, each triad composed of a sense object, a sense organ, and sense consciousness.
The Abhidhamma and post-canonical Pali texts create a meta-scheme for the Sutta Pitaka's conceptions of aggregates, sense bases and dhattus (elements). This meta-scheme is known as the four paramatthas or ultimate realities, three conditioned, one unconditioned:
Form (Material Phenomena)
Mental Factors (The nama-factors sensation, perception and formation)
Enlightenment SN 43:1 (Release DN 15 MN 38 MN 109, the liberation from repeated rebirth in saṃsāra.)
The Truth You Need To Know