A "Course Handicap" is the USGA's mark that indicates the number of handicap strokes a player receives from a specific set of tees at the course being played to adjust the player's scoring ability to the level of scratch or zero-handicap golf. For a player with a plus Course Handicap, it is the number of handicap strokes a player gives to adjust the player's scoring ability to the level of scratch or zero-handicap golf. A Course Handicap is determined by applying the player's Handicap Index to a Course Handicap Table or Course Handicap Formula. (See Section 10-4.) A player's Course Handicap is expressed as a whole number. The result of any conditions of the competition, handicap allowance, or competition from a different USGA Course Rating that changes a Course Handicap is considered to be the Course Handicap.
"Equitable Stroke Control" (ESC) is the downward adjustment of individual hole scores for handicap purposes in order to make handicaps more representative of a player's potential ability. ESC sets a maximum number that a player can post on any hole depending on the player's Course Handicap. ESC is used only when a player's actual or most likely score exceeds the player's maximum number based on the table in Section 4-3.
A "Handicap Differential" is the difference between a player's adjusted gross score and the USGACourse Rating of the course on which the score was made, multiplied by 113, then divided by the Slope Rating from the tees played and rounded to the nearest tenth, e.g., 12.8.
A "Handicap Index" is the USGA's service mark used to indicate a measurement of a player's potential ability on a course of standard playing difficulty. It is expressed as a number taken to one decimal place (e.g., 10.4) and is used for conversion to a Course Handicap. (See Section 10.)
A "net score" is a player's score after handicap strokes have been subtracted from the player's gross score. A plus handicap player adds handicap strokes to the player's gross score to yield a net score.
A "Slope Rating" is the USGA's mark that indicates the measurement of the relative difficulty of a course for players who are not scratch golfers compared to the USGACourse Rating (e.g., compared to the difficulty of a course for scratch golfers). A Slope Rating is computed from the difference between the Bogey Rating and the USGA Course Rating. The lowest Slope Rating is 55 and the highest is 155. A golf course of standard playing difficulty has a Slope Rating of 113.
Definitions that are in italic come from the USGA Handicap Manual