The picture was drawn at the end of January, and it doesn't look comprehensive now. But the classification may be roughly the same.

BTC L2 is undoubtedly a hot spot in the market, and projects are emerging in an endless stream. Many technical experts have also analyzed BTC's L2, which is worth learning. But a lot of professional knowledge needs to be learned, and many friends will feel overwhelmed after reading it! I studied it carefully and made a picture for everyone to understand in vernacular. Because I have a non-technical background, please forgive me for the unprofessional parts.

User experience (customer focus)

Is security guaranteed?

Whether to use native assets (BTC; inscriptions)

Can I use my original BTC address (subjective feeling)

Smooth, low gas, high concurrency (chain performance)

L2 definition (no orthodox definition yet, there may never be an orthodox definition)

Broad sense of L2:

1. Consume BTC as gas

2. With BTC as the underlying asset, it can be used as a dapp platform, and its performance is far better than BTC layer

Narrow sense of L2:

1. Whether it shares security with BTC. If BTC hangs up, can L2 survive alone? The most that can survive alone is called a side chain.

2. Is it censorship-resistant? Will node failures cause the network to be unavailable?

L2 that meets Ethereum standards:

1. Can the first layer verify transactions on the second layer?

2. Can assets on the first layer escape smoothly when the second layer collapses?

3. Add the narrow L2 standard