ATPases are a class of enzymes which are known to catalyze the decomposition of ATP into ADP, along with a free phosphate ion, or to encourage the inverse action. Overall, this reaction releases energy, and the enzyme then usually harnesses that energy to help drive a range of other chemical reactions. In many cases, those reactions would not occur if it were not for this process first taking place. It is a process that is used widely in all forms of life all over the planet.
As part of this process, there is a general importing of many of the metabolites necessary for cell metabolism, and at the same time an exporting of toxins, wastes and solutes that are known to hinder cellular processes. One example would be the sodium-potassium exchanger, which maintains cell membrane potential.
Something you can find in all natural ATPases, and which is therefore considered to be something of a telltale sign of them, is the Walker motifs. This is a protein sequence which is to be found in nearly every ATPase.
The coupling that takes place between ATP hydrolysis and transport is a chemical reaction, so that means that a fixed number of solute molecules are transported for each ATP molecule that becomes hydrolyzed. ATPases thereby harness the chemical potential energy of ATP by performing mechanical work, transporting solutes directly opposite to the direction which is thermodynamically preferred for movement. This is a process known as active transport, and it is a defining feature.