#Drivechain is a combination of two BIPs which allows for the creation of decentralized 2-way peg to move BTC between mainchain and a sidechains.
1) #BIP300 (Hashrate Escrows)
2) #BIP301 (Blind Merged Mining)
The #BIPs can be found here:
Checkout these resources as well to learn more:
Drivechain.xyz
Drivechain.info
layertwolabs.com
BIP 0300 - Bitcoin Wiki
BIP 0301 - Bitcoin Wiki