Can anyone explain Sanskara / Sankara indepth? Can someone provide a canonical explanation to  Sanskara/Sankara?

I appreciate if you can provide some sources,Suttras/Suttas so that i can expand my knowledge.
There's an article in English titled Anicca Vata Sankhara in which Bhikkhu Bodhi describes the various meanings of the word. Here are very brief extracts from that article, a summary:

The word sankhara is derived from the prefix sam, meaning &quot;together,&quot; joined to the noun kara, &quot;doing, making.&quot;

The suttas distinguish the sankharas active in dependent origination into three types: bodily, verbal, and mental.
A second major domain where the word sankharas applies is among the five aggregates. The fourth aggregate is the sankhara-khandha, the aggregate of volitional formations. The texts define the sankhara-khandha as the six classes of volition (cha cetanakaya): volition regarding forms, sounds, smells, tastes, tactile objects, and ideas.
The third major domain in which the word sankhara occurs is as a designation for all conditioned things. In this context the word has a passive derivation, denoting whatever is formed by a combination of conditions; whatever is conditioned, constructed, or compounded.



The suttas
I don't know whether there is a good/long/detailed canonical description in the Suttas.
Suminda's answer references the Abhidhamma.
One of the places it's described is the Paticca-samuppada-vibhanga Sutta, very short:

And what are fabrications? These three are fabrications: bodily fabrications, verbal fabrications, mental fabrications. These are called fabrications.


The aggregates
This page contain three essays by Ajaan Lee. The last essay on that page titled &quot;Part III: The Buddhist Way&quot; describes various types of Sankhara, which is &quot;a brief outline of the Buddha's teachings based on the synopsis of the Ovada Patimokkha&quot;. It includes (again I'm heavily summarizing the article):


&quot;Sankharas on the level of the world&quot;: status, fortune, praise
&quot;Sankharas on the level of the Dhamma&quot;: Dhatu, Khandha, and Ayatana


I think that all khandhas are sankharas, i.e. each khandha is some-things-put-together; for example they include:

Putting things together so that they can be sensed (or more specifically, contact between the sense and sense-object)
Putting a &quot;feeling&quot; with the thing (e.g. &quot;I feel that's good&quot; or &quot;I think that's bad&quot;)

The sense of self (identity view) is presumably a sankhara too (see the simile of the chariot).
The same article also mentions some important attributes of sankharas, e.g. impermanence:

The Buddha taught in line with the true nature of the world. He said, &quot;Khaya-vaya-dhamma sankhara, appamadena sampadetha,&quot; which means, &quot;All sankharas, once they have arisen, decay by their very nature. Don't be heedless or complacent. Be thoroughly mindful and completely alert, and you will attain peace and security.&quot;
What this means is this: All things that appear in the world arising from actions (kamma) are called sankharas — formations, fashionings, compounded things. Sankharas, by their nature, or of two sorts — sankharas on the level of the world and sankharas on the level of the Dhamma.

I may be wrong but I suspect that vipassana meditation might be supposed to help you understand that, at least at the sensory level. I think vipassana is supposed to make you aware of impermanence, but because sankharas are impermanent perhaps &quot;becoming aware of impermanence&quot; means &quot;becoming aware of sankharas&quot;.
I also like the explanation, &quot;All things that appear in the world arising from actions (kamma) are called sankharas&quot;: because I think that helps to explain why sankharas are sometimes translated as not just &quot;formations&quot; but &quot;volitional formations&quot;: i.e. perhaps it's because kamma (action) is also associated with will (see &quot;This volition and the resultant actions constitute kamma&quot; in this commentary).

One of the five aggregates
The terminology turns out to be confusing because all five khandhas are sankharas, but also one of the khandhas in particular is called sankharas.
I think that means &quot;all khandhas are fabricated or put together, but one of the khandhas is what people do when they put things together or fabricate things in their mind.&quot;
Wikipedia summarizes this meaning of sankhara as a specific one one of the five aggregates:


&quot;mental formations&quot;, &quot;impulses&quot;, &quot;volition&quot;, &quot;fabrications&quot; or &quot;compositional factors&quot; (Skt. samskāra, Pāli saṅkhāra, Tib. 'du-byed): all types of mental habits, thoughts, ideas, opinions, prejudices, compulsions, and decisions triggered by an object


This too matches (is an even better match for) the &quot;volitional formation&quot; translation.
The footnote to that Wikipedia paragraph begins with, &quot;The Theravada Abhidhamma divides saṅkhāra into fifty mental factors&quot;.

All conditioned things
There's an example of this usage in the Buddha's last words (in the The Mahāparinibbāna Sutta),


And the Blessed One addressed the bhikkhus, saying: “Behold now, bhikkhus, I exhort you: All compounded things are subject to vanish. Strive with earnestness!”58

This was the last word of the Tathāgata.

The footnote gives the Pali,

Handa dāni bhikkhave āmantayāmi vo: Vayadhammā saṅkhārā appamādena sampādetha.

Jayarava explores that phrase, and how difficult it is to translate, in this article, The last words of the Buddha.