Hammer and Anvil Technique
The hammer and anvil technique for removing flakes from a core is perhaps one of the oldest documented methods. It is quite effective for making large flakes for direct use as tools, or for use as blanks from which shaped tools can be made. This technique entails using the core as a hammer, and striking the edge of the core against a large, stationary rock (the anvil) in order to remove a flake.
Bipolar Technique
The bipolar technique is a modification of the hammer and anvil technique. In bipolar flaking, the core is placed on the anvil for support, and then struck with a large heavy hammer. The compression from both ends of the core cause it to shatter into hundreds of flakes, some of which will be large enough, and of the right shape for use as tools. This technique is often found in areas where the only reliable source of workable stone is rounded river cobbles that are extremely hard to work in any other fashion.