# Concepts

- [BEEF](/guides/sdks/concepts/beef.md)
- [Fees](/guides/sdks/concepts/fee.md)
- [SPV](/guides/sdks/concepts/spv.md)
- [Transactions](/guides/sdks/concepts/how_tx.md)
- [Op Codes](/guides/sdks/concepts/op.md)
- [Script Templates](/guides/sdks/concepts/templates.md)
- [Signatures](/guides/sdks/concepts/tx_sig.md)
- [Verification](/guides/sdks/concepts/tx_valid.md)