Interracial means happening between people of different races — an interracial marriage, friendship, school, or neighbourhood. It is a serious word, often used in news, law, and school writing, when race is the point of what you are naming. Though actually, it does not only mean marriage, even though that is the phrase many learners meet first; a team or a street can be described this way too. And this ‘race’ is about human groups, not a running race to the finish line. In careful talk today, some people prefer words like mixed, or they name the groups, but interracial is still widely used, especially in US English and in formal writing. Use it when you mean it; do not throw it at every story that happens to include people who look different.