There is a system of aspects to the Force of which there are many variants. Note that I use the words 'aspect', not 'side' and there is a very good reason for this. By using the word 'side', you are suggesting that each side is a separate entity of an overall picture. Whilst this concept may be explainable, it requires some advanced thought patterns that may be misleading at the basic level that the human mind most commonly interprets them. As a result it is much less misleading on a conscious and subconscious level to use the word 'aspect' which merely means a 'view' or 'perspective'.
There are many people who you will come across that have chosen to use the title of Shadow to represent them but the first thing that should be noted is that the title of Shadow does not have any one fixed definition, nor does it have two or three firm set areas within it.
The Shadow is a complex concept and often you will see the title of Shadow being used hand in hand with two other titles, those of 'Uber' and 'Grey/Gray'.
I could tell you of three distinct types of Shadow that I have come to know, and also how the titles of Uber and Grey fit in.
There has been great confusion over these various titles as there are some that believe each to be representative of a different set of people, whilst at the same time there are those who believe that all three titles mean the same thing. It is important not to make assumptions about what another means when using any of these three titles, or for that matter any other titles.
I shall attempt to convey a short summary of the various concepts as relating to each title that I have come across at various locations.
First off, I have seen people who say that they can pick and choose at will between the Light and Dark and basically do whatever they want, whenever they want without becoming a part of either 'side'. I have noted these people to use any one of the three titles, and they may infact be those that believe the three titles to have the same meaning.
There are then two concepts based upon maintaining a balance of the Light and Dark. One concept is that people following this path walk the fine line where the Light and Dark meet, the other concept being that Light and Dark are set, defined extremes and the balance is the grey area which spans between the two extreme. Now I have come across such people using the titles of either Shadow or Grey/Gray, yet I have yet to see an Uber pertaining to either of these paths.
The third 'version' is unlike the others in that it does not base itself on the Light and Dark. Now this opens up a Pandora's box of ideas in that it is near impossible to surmise all the concepts as with the other ideas. These are people like myself. I use the title of Shadow but I also know of people with similar ideas that use the title of Grey/Gray. The only way I can sum this up is that the definition of the title in this case bends to the person using it, not the other way round.
My personal way of working is to seek out new knowledge and ideas, to see how they compliment each other and assimilate them into my understanding. I learn of alternative perceptions, the reasons why each person has chosen them and what benefits/drawbacks that they give.
Now most people find a way of thinking or a particular perception that they think suits them fine, and they stick with it because it provides security and a steadfast way to advance.
This has is benefits though I find it restrictive so I strive to take into account all the perceptions that I know, not just the one that suits me best. I find something that I can see at the heart of all the perceptions and this, I believe is as close to the truth as anyone can get.
The truth cannot be explained with words, nor can it be classified into perceptions...but then again, that is another story.
Peace be with you.