Racism

Racism is a term that is used every day by people around you. Whether in a joking matter or in a serious conversation the word racism is always used. But what does racism really mean? People have different ideas of what race and racism is. There is the obvious idea of stereotyping or attacking one specific race but if one says something "joking" is it considered racism? Also, is making racial comments alright now a days? Usually you find people making fun of their own race or using stereotypes targeting their own ethnicity. Most of this is overlooked so is this an input to why racism is so impossible to halt?