Inlet Pumps are mechanical devices which transfer liquids (Water, Honey or Lava) to an attached Outlet Pump. The Inlet Pump will only function if it is attached to an Outlet Pump.
To operate a set of Pumps, the player must place a Switch, a Lever, a Pressure Plate, or a timer in the Wire between the two Pumps; each time it's activated, some of the liquid will flow from the Inlet to the Outlet.
Pumps are popular for building traps, particularly when used in conjunction with Lava. Additionally, they can be used to move large quantities of liquid from one place to another with comparative ease, and without the use of Buckets. It can also be used to farm certain materials, though this is likely not intentional. (See 'Bugs', below)
Pumps take up a 2-by-2 space, and require two solid blocks to sit on; if either one is destroyed, the Pump will break for pickup.
If an In/Outlet Pump is submerged in a liquid, it will not work until the liquid submerging it is gone.
Combining the liquid Pumps with a Lava drainage system (e.g. Gravestone half-submerged in Lava under an overflow point) can create an endless waterfall effect with the excess pouring over the sides and evaporating on the Lava.
Liquids being pumped do not always exactly maintain their volume, and frequently increase slightly in transit, especially if the inlet pump is completely submerged. This means in most cases cycling fluids (through 1 or more pumps) will replicate themselves infinitely, though for low volumes they will sometimes drain away to nothing. Adding 1 or more intermediate sets of pumps may have a stabilizing effect, though this is as inconsistent as the issue itself, and often increases the rate of growth.
There is roughly a 1000 block (2000 feet) limit liquids can be pumped.