A good catcher makes difficult catches look easy and impossible catches look gettable. It is often said that if you get a hand to a disc you should catch it.
Australian Ultimate: Catching
Using two hands is essential for catches from just below the knees to just above the top of the head and at least a foot either side of the body. There are a few different styles of catching, used under different circumstances. Most straightforward catches will use the pancake style, while harder passes, particularly those when the receiver is running at speed may use the crocodile style. Only catches that are too high or two low to be caught safely with palms facing each other should be caught with both hands on the rim.
Pancake Catch: Whenever possible, catches should be attempted two-handed, with the palms facing each other. The pancake style is close to the body, with hands at right angles to each other. The receiver should attempt to get their body behind the direction of travel of the disc. It has the advantage that if the catch is mistimed, there is a good chance that the disc will hit the body of the receiver and still be caught between the hands. This is the style that should be used for the majority of throws as it is least prone to error.
Crocodile Catch: The crocodile style is out in front of the body with arms almost parallel, and often with some of the impact being absorbed by the fore-arms. As for the pancake catch, the receiver should attempt to get their body behind the disc. The reason in this case is to get the arms in line with the direction of travel of the disc. The main use for this type of catch is when the disc is travelling at speed relative to the receiver. The forearms provide a longer area to decelerate the disc over, and hard throws are less likely to be dropped. The disadvantage is that because the arms are roughly parallel, the disc has a tendency to flip out sideways if the arms do not move directly up and down towards each other.
Rim Catch: Catches with both hands on the rim are risky and rarely necessary. They should only be used if the disc is well above the head or the around ankles, and in the latter case only when it is not possible or reasonable to dive or slide to catch it. The disc should be caught with both hands on the leading edge, one hand on either side of the disc. The reason rim catches are risky is that they have a tendency to spin out of the hands sideways, a tendency which is stopped by catching the disc on top and bottom.
Layout catch: Often, it is necessary to layout in order to get near enough to the disc to attempt a catch or to get away from striving defenders. The style should be either a "crocodile" catch or a rim catch, preferably the former. Two-handed layout catches may well be more difficult than one-handed because it is harder to cushion the impact with the ground. This impact often dislodges the disc, and is called a ground strip. To avoid being ground stripped, the catcher should try to keep the arms from hitting the ground, and use the rest of the body to take the impact. This is one time when a rim catch has the advantage, because once the disc is in the hands, it is much harder to dislodge.
A one-handed catch should be attempted anywhere where it is difficult or impossible to catch with two hands. Having to stretch a bit or avoiding falling on the ground is not an excuse for catching one- handed. Catches around the ankles, well above the head, or far to either side must necessarily be caught with one hand. When the disc is skied above receivers and defenders heads in the air it is usually most advantageous to contest it with one hand. If the disc is above the elbow, it should be caught thumb down, otherwise thumb up: experience will show the difference.