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.
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