| Quoits is a traditionally English/Welsh/Scottish game very similar to American horseshoes. Outdoor Quoits can be played with horseshoes as well if the players can't afford to buy the flat metal (or rubber) rings, also called "quoits."
The most traditional form of Quoits is is played outdoors with heavy steel (or iron) rings. These heavy rings were originally used as weapons of hunting and war by the ancient Greeks, and can still be used as a weapon (lawn darts come to mind). The quoits are thrown 11 to 21 yards1 at a stake placed in a clay pit.
A traditional English quoit weighs 5.25 lbs (2.4kg). It is rounded on one side and slightly concave on the other (cheaply-made traditional quoits will be flat on one side rather than concave). It is 8.5 inches in diameter, with the center hole being 5.5 inches in diameter.
A traditional Scottish/Welsh quoit, also called a Celtic quoit, weighs 9 lbs, being that the center hole is only 4 inches in diameter on a 8.5 inch quoit.
Both kinds of traditional quoits will eventually rust. Due to this oxidization (and the danger of throwing such a heavy ring), it is not unusual for outdoor quoits to be played with nontraditional quoits.
There are huge variations in the size, number, and game layout of rings and pegs in nontraditional and indoor Quoits. The sources below include pictures, history, expanded discussion on the many variations of Quoits, and names of pubs where Indoor Quoits can often be played (Most of these pubs are in Powys, Evesham, Worcestershire, Herefordshire, and Gloucestershire).
1 The Long Game is played with a stake placed 18 or 21 yards away; the stake is driven almost entirely into the clay and is barely visible. The Northern Game is played with a stake placed 11 yards away; the stake juts slightly out of the ground. This allows for more strategy, as the first thrower can attempt to block the stake to sabotage the second player's throw.
Sources:
http://directory.google.com/Top/Games/Yard,_Deck,_and_Table_Games/Quoits/ | 
