A Side Chain pertains to a blockchain ledger that is parallel to a primary blockchain. A two-way link between the primary chain and sidechain is existent, allowing for the sidechain to work effectively on its own. Hence, the help of the primary blockchain is no longer required. The sidechain cold already function through its own protocols or ledger mechanisms.
A Side Chain allows its users to move his or her Bitcoin to another blockchain. The coins can be traded through this and then moved back to the main Bitcoin blockchain.
Given that sidechains are separate systems, technical and economic innovation are not hurdled.