Identifying the Ball - Except in a hazard, players may, without incurring a penalty, lift a ball they think is theirs and clean it for purposes of identification. After doing so, they must put it back in exactly the same spot from which they took it. However, most golfers are aware that in the few seconds needed to complete this manoeuvre, the earth itself has moved in a number of directions, both because of its own rotation and due to the movements it shares with the solar system and the galaxy, and they compensate for these motions by shifting the position of the ball from, say, the muddy divot hole from which it was removed to a point a few trillionths of an Astronomical Unit away (about a foot) occupied by a nice tuft of grass.

Iffy Lie - A questionable lie, where it is uncertain how the ball will react when struck.

Impossible Lie - A ball that is in a position that is both completely obstructed by an immovable object and continuously observed by an incorruptible player.

Interlocking Grip - To hold the club such that the little finger of one hands is wrapped around the fore-finger of the other.

Instruction - Golf is virtually impossible to learn from a book, and some personalised instruction is absolutely essential, but there are a handful of simple admonitions that every player would do well to commit to memory:

* Don't lock your knees.
* Don't bend your left arm.
* Don't loosen your grip.
* Don't pick up your head.
* Don't count out loud.
* Don't write in ink on your scorecard.,

Interlocking grip - Grip style where (for right-handed players) the pinkie finger of the right hand is hooked around the index finger of the left.

Inward Nine - The back nine holes, so named because older links courses were designed to come back "in" toward the clubhouse after going out on the front nine.

Iron - A club with a flat-faced solid metal head generally numbered from 1 to 9 indicating increasing loft.