What are the trample rules in Magic: The Gathering and how do they affect gameplay?

In Magic: The Gathering, trample is a keyWord ability that allows a creature to deal excess combat damage to the defending player or planeswalker if it has trample and its power is greater than the toughness of the creature blocking it. Trample affects gameplay by giving attacking creatures with high power the ability to deal damage beyond what is needed to destroy blocking creatures, potentially dealing more damage to the defending player or planeswalker.