The Bitcoin network has several layers which enable users to use their bitcoin outside of the Bitcoin blockchain. Examples of layers include the Lightning Network and the Liquid Network. Layered solutions allow innovation without threatening Bitcoin's security.
A light client is a Bitcoin application, such as a wallet, that does not store the blockchain. Instead, a light client queries other nodes for specific transactions or blocks of interest. Light clients are less private and trustworthy than nodes, but are more convenient and less demanding of disk space.
A Lightning channel is a connection between two parties enabling instant, cheap transactions between the two parties. The Lightning Network is composed of thousands of channels.
The Lightning Network (LN) is a protocol designed to allow instant and cheap Bitcoin transactions. While it is still experimental, it shows great promise for Bitcoin’s ability to scale.
The Liquid Network is a sidechain protocol built on top of the Bitcoin blockchain. The Liquid Network offers several features not offered on the Bitcoin blockchain