I was genuinely planning on not replying until 2021, but I think 2 months is enough time for you to learn the lesson to not insult my fragile little self. Apologies for the delay. I'm just as bad at responding to my own shit than I am to others...
Okay, so, I'll just come out and admit it, I have trouble wrapping my head around the intricacies of Sealing, so I'm going to refer to the ability rule thread, and do my best to break down my understanding of it as I read through it, and boil it down to the most basic elements I can understand. However, as a starting point, I do understand that Sealing is used to seal things.
From physical objects and things like tools all the way to other Jutsu, all the way up to more metaphysical concepts, such as Chakra, one's own memories, psyche, and that infinite technicolor rainbow in-between, these are what's known as the "Target" of the Sealing technique. Examples of this would range from Tenten's scrolls which contain tools, to Kabuto sealing cadavers within his own scrolls, to Kushina and Minato sealing imprints of themselves within Naruto, which would be released upon the Nine Tail's seal becoming undone, willingly or not.
As far as I can tell, the next part would be the "Binding" of a sealing technique, which is essentially the script which envelops the Target, and seals it. From the gif shown in the Fuinjutsu Ability Rule thread, it shows an Uzumaki Elder weaving seals, before placing their hand on the ground as the sealing script travels to his Target, which I assume is some form of animal. This would then be sealed within the next part of a Sealing technique.
Regardless of what's sealed, it must be contained within some form of medium. In the case of Ninja Tools, other Jutsu, etc, you would typically use a scroll, and for more advanced concepts, they can be more unique mediums, such as yourself (Which, as I understand it, is now sealed behind Kinjutsu and Advanced Fuinjutsu). Danzo's seal he used at the end of his fight with Sasuke is an example of this, as had the seal placed onto his body, and it activated in the moments leading up to his death, with the seal activating at that point, and not only pulling himself, but also everything within the vicinity into a singularity-like pull, crushing everything, such as his body, to prevent people using it to learn the secrets of his and Orochimaru's experiments. This would be the "Medium" or "Vessel" of a Sealing technique.
Then there are two potentially optional parts of a Sealing Technique, the "Trigger" and the "Key". In regards to a trigger, the only one that comes to mind is the one that the rules mention; Danzo's Juuinjutsu, which is applied to members of Root, and activate upon them speaking of him in almost any manner, to prevent information about him from being leaked. This, I guess, would be an audible trigger, but I have to assume others exist, such as timed triggers, hand-seal-based triggers, etc. The key is, essentially, the same thing, but in reverse, undoing the seal, and bringing forth what has been sealed.
As for the last one the rules mention, personally I think it's not relevant to mention. Sealing Techniques are an advanced form of Ninjutsu, so, to me, it's only natural they would utilize and consume Chakra to perform, maintain and release. I guess the reason why this is mentioned is to point out that a Jinchuriki's Chakra is used to maintain their Tailed Beast's respective seal, not the sealer, but I can't see why that would otherwise be relevant to Sealing techniques. Just strikes me as common sense.
Finally, I'm aware that Barriers are, for some inexplicable reason, considered Sealing Techniques, but this is where my brain does not compute, and just gives up, as they aren't sealing anything. Only example I know creates a barely translucent field around the user in a certain radius, and notifies them of anything entering it's area of effect. If you could explain this to me in the simplest manner possible, you could save my poor brain from blowing up.
And that about sums up my understanding of Fuinjutsu, and it's 6 component parts.