also: unbalanced line · tackle over · tackle-over
Putting more linemen on one side of the center than the other. Legal, rare, and disruptive, because a defense's alignment rules are written assuming five linemen in the usual places.
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The offensive line aligns with more players on one side of the center than the other, most commonly by moving a tackle to the other side of the formation, which is where "tackle over" comes from.
The reason it works is that it moves the edge. Defensive alignment rules are written in terms of the offensive line, so a defense that aligns by rule will align to a line that is not where it thinks it is, and a defender who believes he is the end man is suddenly inside somebody. Against a defense that does not check it, the offense gains a blocker at the point of attack without adding a player.
unbalanced line, tackle overtrips, split end, flanker and slotRearranging the line changes which players are on the line of scrimmage and therefore which receivers are eligible. A formation can cover up an intended receiver and make him ineligible by alignment.