The (Buddhapada) are one of the early representations of the Buddha in the anticonic (no statues) stage of Buddhist art. The Buddhapada are highly revered in all Buddhist countries, especially in Sri Lanka and Thailand.
Symbolizing the grounding of the transcendent, feet have been objects of respect in India long before Buddhism. According to Buddhist legend, after the Buddha attained enlightenment, his feet made an imprint in the stone where he stepped.
In another tradition, the infant Buddha took seven steps after his birth to symbolize his spiritual domination of the universe.
The symbolize the Buddha's presence, as they are believed to be the imprints where the Buddha actually touched the ground. At the same time, the Buddhapada signify the Buddha's absence now that he has entered nirvana, and thus are a reminder of the Buddhist ideal of nonattachment.
The Buddha's footprints are usually depicted with the toes of all one length and with a dharmachakra(wheel) in the center.
Other early Buddhist symbols also appear on the heels and toes, such as the lotus, the swastika and the triratna(Three Jewels).
Some Buddhapada can be very large and detailed, displaying the 32, 108 or 132 distinctive marks of a Buddha in a checkerboard pattern.
These symbols are also seen on the bottom of the feet of large statues of the reclining Buddha.
Sculptures of Buddha's footprints are usually protected in a special temple structure, where the faithful bring flowers and other offerings to them. The Buddhapada image can also be found on Tibetan thangkas.
Source : religonfacts.com