I think that English speakers divide the space in two parts: here and there. If something is near and you can touch it, it" s hear. The rest is there. Spanish speakers divide the same space in three parts: the nearest one is "aquí"; the following part is "ahí" and the most distant one is "allí". To sum up, "here" is "aquí", and "there" is "ahí" and "allí".

Aquí/Acá = Here Ahí = There Allí/Allá = There