Ahí : when it's close Allí: when it's far

Carlos' answer is not wrong but I don't know why someone gave him a "thumb down" so I gave him one up. There are three different "levels" defering to distance from an object or a place in Spanish. "Aquí" or "Acá" (less used in Spain) means "here". "Ahí" means "over there" most of the times and "there" when what we're refering to is relatively not far away. "Allí" and "Allá" mean "there" when what we're talking about is relatively far away, but "allá" is even more emphatic: Example: "No quiero ir hasta allá, ¡está denasiado lejos!" (I don't want to go there, it's too far away!) I hope it helps.