SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation.
On most plays, the center will snap the ball directly into the quarterback's hands. In a shotgun formation, the center snaps the ball to the quarterback lined up several yards behind him.
A halfback is the holder of an offensive position in American football whose duties involve lining up in the backfield and carrying the ball on most running plays in formations such as the veer variant of the wishbone.