By using gravity to move objects or substances downward, a tower can be used to store items or liquids like a storage silo or a water tower, or aim an object into the earth such as a drilling tower.
The ubiquity of modern skyscrapers has robbed the word tower of most of its meaning, though the Petronas Twin Towers in Kuala Lumpur, Malaysia, the Willis Tower in Chicago, and other skyscrapers still bear the term in their official names.