"The I formation is one of the most common offensive formations in American football. The I formation draws its name from the vertical (as viewed from the opposing endzone) alignment of quarterback, fullback, and running back, particularly when contrasted with the same players' alignments in the T formation.
The formation begins with the usual 5 offensive linemen (2 offensive tackles, 2 guards, and a center), the quarterback under center, and two backs in-line behind the quarterback. The base variant adds a tight end to one side of the line and two wide receivers, one at each end of the line." [I formation. Wikipedia]
The American football positions diagram example "I Formation (Offense)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.