Refers to a concept of storing Bitcoins in one’s own mind by memorizing a pass phrase. So long as the pass phrase is not recorded anywhere, the Bitcoins can be thought of as only existing in the mind of the holder. The holder of the cryptocurrency stores a private keys as a memorable pharse without any digital or paper trace. Either a single key is used for a single address, or a deterministic wallet is derived from a single key. A brain wallet greatly reduces the risk of theft. However it is prone to errors when the owner forgets the secret phrase, or the phrase is too simple and therefore prone to hacking. Additional risks result from required complex software.
Malone, J.A (2015). Glossary of Bitcoin Terms and Definitions. United States: Lulu Press, Inc