A footprint is the arrangement of pads used to attach a component to the PCB (printed circuit board). In simple terms, A footprint on a circuit board is a copper area where a component is soldered. Copper layout, silkscreen, solder mask layout, mounting holes where applicable, solder paste, courtyard and pin attributes are included in the footprints.
A set of predefined common footprints and custom footprints that you can create are available in the footprint library. The characteristics of a footprint will vary depending on the component’s mechanical dimensions and tolerances, the standards used to create the footprint, and the requirements for design.