The anchoring rule in golf - Rule 14-1b - goes into effect on Jan. 1, 2016. What does the rule say? What does the rule mean for golfers? Here is an explanation in the form of a video from the USGA, and below that more details about the rule:
To recap the video: The anchoring rule bans certain types of strokes, but does not ban any putters. If you have a belly putter or long putter, you can keep on using it, and those putters will continue to be sold.
However, any golfer who anchors those or any putters to his or her body - anyone who holds the putter in such a way as to create a stable anchor point by pressing against one's body - will have to switch to a different method of stroking the putt in order to abide by the anchoring rule.
Here is the R&A's own video explaining the anchoring rule, which contains some of the same info but also makes additional points:
Here is the actual wording of the anchoring rule:
14-1b Anchoring the Club
In making a stroke, the player must not anchor the club, either "directly" or by use of an "anchor point."
Note 1: The club is anchored "directly" when the player intentionally holds the club or a gripping hand in contact with any part of his body, except that the player may hold the club or a gripping hand against a hand or forearm.
Note 2: An "anchor point" exists when the player intentionally holds a forearm in contact with any part of his body to establish a gripping hand as a stable point around which the other hand may swing the club.
You can read much more about the anchoring rule on the USGA or R&A websites.