The sodium-potassium pump is maybe the most well-known pump in biology, and rightly so as it is extremely important for life.
This pump functions by hydrolysis of ATP for energy, and by doing so <em>pumps 3 Na+ molecules to the extracellular space and 2 K+ molecules to the intracellular space.</em> This creates a higher sodium concentration outside the cell and a higher one inside the cell.
This gradient has several functions, such as helping maintain electrochemical neutrality and providing the adequate gradient of cations for signal transduction in neurons, to name a few.