Presser foot

A presser foot keeps the fabric flat so that it does not rise and fall with the needle and pucker as it is stitched.

Presser feet are typically spring-hinged to provide some flexibility as the workpiece moves beneath it.

Presser feet have two toes, one to hold the fabric down on either side of the needle.

[1] Different manufacturers have produced machines with one of three types of presser foot shank in mind.

Among these are the following:[2][3] Most presser feet are made of steel or clear plastic; however, presser feet made of Teflon or other non-stick material are used for sewing with leather, plastic, vinyl and oilcloth.

A sewing machine presser foot.
A diagram of the three principal types of presser feet— the high-shank foot, the low-shank foot, and the slant-shank foot— used in domestic sewing machines
Snap-on presser foot on a Singer Promise 1409