A pile is one type of building foundation. Piles are used when the soil near the ground surface is not strong and the weight of the building must be carried by deeper soil layers. The strength or bearing capacity of the soil can be measured using a cone penetration test.

Historically, piles were wood, later reinforced concrete and pre tensioned concrete.

Piles can be prefabricated and driven into the ground using a vibrator or a diesel pile driving rig supported on a drag line excavator, or can be formed in situ in a bore hole.

Steel sheet piles can be used to construct retaining walls.

See also Geotechnical engineering.

Piles is a synonym for hemorrhoids.

Pile is a measure of the fibre length in carpets.

A pile is the working part of a nuclear reactor.

In heraldry, a pile is an ordinary, a downward-pointing triangle reaching from the top of the shield to its bottom, and occupying its full width.