The Extra point reference article from the English Wikipedia on 24-Apr-2004
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Extra point

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The extra point is, in American football, the act of lining up to kick, as in a field goal, immediately following a touchdown. If the kick goes through the uprights, the team gets an additional point for their touchdown, bringing their total for that score to 7.

If more points are needed or desired, a two-point conversion may be attempted instead of the extra point kick.

The extra point is often referred to as the "PAT," which is an abbreviation for "point after touchdown."