COMMUNITY

"Practice strokes." A player must not make a practice stroke during play of a hole. Between the play of two holes, a player must not make a practice stroke, except that he may practice putting or chipping on or near:

(a) the putting green of the hole last played,
(b) any practice putting green, or
(c) the teeing ground of the next hole to be played in the round,

provided a practice stroke is not made from a hazard and does not unduly delay play (Rule 6-7).

Strokes made in continuing the play of a hole, the result of which has been decided, are not practice strokes.

Exception: When play has been suspended by the Committee, a player may, prior to resumption of play, practice (a) as provided in this Rule, (b) anywhere other than on the competition course and (c) as otherwise permitted by the Committee.

PENALTY FOR BREACH OF RULE 7-2:
Match play â€" Loss of hole; Stroke play â€" Two strokes.
In the event of a breach between the play of two holes, the penalty applies to the next hole.

Changing Golf Balls (type or brand).. Interesting, I didn't know this.
Rule 15-1

Changing golf balls during a hole or a stipulated round

Q. May a player change golf balls during the play of a hole or a stipulated round? When the player is permitted to substitute another golf ball may he change to a ball of a different brand or type?

A. Rules 15-1 and 15-2 explain that the player must complete play of the hole with the ball with which he began the hole unless he is proceeding under a Rule that permits him to substitute a ball. The player may change balls between the play of two holes as well.

Rules 26-1 (Water Hazard Rule), 27-1 (Ball Lost or Out of Bounds) and 28 (Ball Unplayable) are examples of Rules that permit the player to substitute another ball. Rule 5-3 permits a player to substitute another ball during the play of a hole when his original ball has become unfit for play during the play of that hole. Other Rules (e.g. Rule 18, Rule 24, and Rule 25-1) permit the player to substitute another ball only if the original ball is not immediately recoverable.

Note that Rule 16-1b, the Rule that allows the player to lift his ball from the putting green, does not permit the player to substitute another ball; this precludes the player from substituting a “putting ball.”

A player who substitutes another ball when not permitted to do so incurs the general penalty (loss of hole in match play or a two stroke penalty in stroke play) under the applicable Rule. For instance, a player taking relief, without penalty, under Rule 25-1 due to interference from ground under repair is required to do so with the original ball (unless it is not immediately recoverable). If that player substitutes a ball (and makes a stroke with it) when his original ball is immediately recoverable he incurs the general penalty under Rule 25-1 (as it is the applicable Rule in this case).

When changing balls, the player is permitted to substitute a ball of another brand or type unless the Committee has adopted the One Ball Condition of Competition (see Appendix I; Part C; Section 1c). This optional condition (usually referred to as ‘The One Ball Rule’) is generally adopted only in events that are limited to professional golfers or highly-skilled amateur golfers. Generally, this condition of competition is not adopted in club-level competitions.