Why does baking soda and vinagar fizz?

What would make vinegar bubble up? The answer is baking soda.You should fill up half a cup and put a BIG SPOON-FULL of baking soda and it bubbles up.Do this in a sink or outside.Also wear old clothes do you don't get stained.Thats exactly what you use to make vinegar bubble up.So the answer once again is BAKING SODA:)