Explore the latest development of Bitcoin Layer 2 technology, and understand key technical routes such as state channels, side chains, Rollup, and UTXO+ client verification. The article analyzes the progress of major projects such as Lightning Network, Stacks, and Rootstock, as well as emerging technologies such as Merlin Chain and Fractal Bitcoin. It also reveals the financing boom in the Bitcoin Layer 2 field in the past five months, as well as the challenges and future trends facing the industry.