The I formation is an offensive formation in which the quarterback is under center, a full back is lined up directly behind the quarterback, and a tailback is lined up directly behind the full back.

The I formation is one of the most common formations used at all levels of football.  The formation above is called I-left in most offensive schemes.  The left designates where the tight end is aligned.  Note a split end to the far side of the formation and a wide receiver to the near side.  While not necessary for an I formation, this arrangement is very common.

There are two main variations on the I formation.  The first variation is called an off set I.  It is so named because the fullback is no longer in a line with the quarterback; he is off set to one side.

Sometimes instead of having a receiver, an offense will opt for another blocker in the backfield.  This additional fullback lines up next to the I formation full back to create a power I formation.

Gridiron Glossary is a resource for football terms that are often used by commentators, coaches and players but rarely defined.  If there is a term you have questions about or a definition you don’t agree with, let me know at billy@thirddowndraw.com.