Drivechain allows Bitcoin to create, delete, send BTC to, and receive BTC from “Layer-2”s called “sidechains”. Sidechains are Altcoins that lack a native “coin” – instead, BTC must first be sent over.
BIP 300: https://github.com/bitcoin/bips/blob/master/bip-0300.mediawiki
BIP 301: https://github.com/bitcoin/bips/blob/master/bip-0301.mediawiki
Learn more about Drivechain here: http://drivechain.info
For an example sidechain implementation, see: https://github.com/drivechain-project/sidechains
Bitcoin Core (and Drivechain) are released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.