Racism is merely the ignorant way of creating irrelevant separations' and boundaries' between human beings that look differently, based on their origins within the planet. See, once you take away the feelings behind this primitive way of thinking, and call it like it is, on a larger scale, you can see just how idiotic racism is. Racism is basically an idea of separation, fueled by emotion, that compels an individual to create an imaginary hierarchy, where this individual is higher than you because of mere differences. It's this bully tactic, that has presented itself many times in different forms within history, that superiority, traditions and ignorance, are going to be blamed as main factors, for this racism complex.
(1) Some may say that the idea of superiority is a basic human trait that is learned through the environment you are raised under. It's a flawed, and often, under explained complex that naturally adopts emotions of narcissism, hatred, and dominance into play. Once someone feels they're superior over you, all conversations, efforts and even thoughts turn into a very biased and subjective offense towards you, in which, allows racism to make a nice, snug fit in between. Superiority is a weapon that is used to describe advances in groups of people that use differences as ammunition to fire bullets of racism throughout the planet. Since the idea of superiority is a trait that can be learned, rather than inherited by genes, you have to look at traditions as the next pillar for racism.
(2) There was once a story about a well-off mom that used a small pot to make food for a rather large family. The child of this mother grew passed the uniformity of just accepting the idea that a small pot should be used, over a large one, so the child asked why. The child went down the line of his/her elders, only to come to the conclusion that the great-grandmother couldn't afford a large pot back in her day. It was this tradition, that was being passed down by generation, blindly, with no challenge, that caused this family to waste time, energy and life. All over something so stupid that could have been corrected, had someone challenged the tradition sooner.
Traditions of racism have always been blindly passed down without challenging or using original thought, leading to the very demise of human progression towards unity and making us look ignorant from the outside in.
(3) Ignorance, in short, is a frame of mind that lacks knowledge and wisdom. It's the very traditions that continue to present themselves generation after generation throughout groups of people that feel their superior over others, because of mere differences. Ignorance is refusing to take a step back and open up to newer ideas. It's a wrench thrown into the machine of progression and unified growth.
All these negative characteristics of superiority, unchallenged traditions and ignorance, pump life towards racism. Racism it a hate guided feeling, inflicted to make the very definition of "other", possible. It's like a cancer that will continue to spread, until you can get humanity to be more unified, challenge traditions and intelligent in seeing the bigger picture of life. Humans are one organism, and these imaginary segregations that we keep allowing to exist, will only hinder future human advancement, and lead us down an inevitable rabbit hole of self destruction.