when you complete a series of downs to start another,for example,if it is 3rd down and 3 yards and you get it it is an conversion.
A conversion can also mean a point after touchdown or a two point conversion after a touchdown.
1 point
Two points, from what i heard
2 point conversion
1958
The NFL adopted the 2 point conversion in 1994.
Attempt a two point conversion
The modern-era two point conversion, by run or pass, started in 1958.
1958
Click on the Related Links below for the NFL 2 point conversion chart.
Safety and a 2-point conversion
You can, but it' very rarely works.
Obviously its two points for the returning team.