> For the complete documentation index, see [llms.txt](https://docs.zecrey.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge.md).

# Crypto Knowledge

- [Layer 1 (L1)](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge/layer-1-l1.md)
- [Layer 2 (L2)](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge/layer-2-l2.md)
- [ZK-Rollup](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge/zk-rollup.md)
- [Gas Fee](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge/gas-fee.md)
- [NFT](https://docs.zecrey.com/education/concepts-explained/crypto-knowledge/nft.md)