"Racism" being when someone treats a person in a certian way (including assuming things about them), or abuses them, or makes excuses for them, based on race.
Example 1: "If you are arabic, you must not drink alcohol, since you're arabic."
Example 2: "I do not like -name- because he/she is asian"
Example 3: "Since you are black, you should be given a free place in a university, because your ancestors were enslaved. For diversity, of course."