Why do people discriminate?

I feel people discriminate because they do not understand others culture, values, traditions language etc.

What I beleive is, if you try to understand other people you won't discriminate any longer.
Discriminating against another fellow human being = ignorance.

Ignorance = Misunderstandings.

I do not know if this can be the root cause of discrimination or not?

Personally what I have felt is more you try to be friends (understand) with people from other race/religion/colour, chances are that you are less likely to discriminate.

Also, sometimes it is upto a society to look into itself and see why they are not being accepted.
Maybe their hardcore beleifs do not fit in this 'More Free World'.

If you come to another country you should fit in, if they are too offending to you; may be you should go back home. Because if you carry your own attitudes you will get strange reactions, because people may not be aware of them. Well if you cannot accept them, how can you expect others to understand you.

p.s.: This post is not supposed to offend anybody. Just some thoughts.