Many things can create one, ...
Many things can create one, it can be of any shape or size, it is created for various reasons, and it can shrink or grow with time. What is it?
Best friends???
Frank and Jim, are walking down the street when Jim turns to Frank and says, "Frank, if you had two of those top-of-the-line Mercedes Benz cars, with all the gear, electric windows, CD player and all of that, exactly the same, would you give me one?"
Frank says, "Jim, how long do we go back? Thirty years? We've been best friends since school, and if I had two of those Mercedes, top-of-the-line cars with all the trimmings, exactly the same, yeah, I would give the other one to you."
So, they keep walking. After a couple of minutes, Frank turns to Jim and says, "Jim, if you had two of those luxury type yachts, you know, with all the modern conveniences, and they were exactly the same, would you give one of them to me?"
Jim says, "Frank, you and me are like brothers, you were best man at my wedding, you attended my son's wedding, we have gone to the same lodge together for all these years. If I had two of those luxury yachts, exactly the same with all the modern conveniences, then yeah Frank, I really would give the other one to you."
They keep walking. A couple of minutes later, Jim turns to Frank, "Frank, if you had two chickens..."
"Now hold on there! Jim, you KNOW I've got two Chickens!"