> For the complete documentation index, see [llms.txt](https://docs.nubit.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nubit.org/utxo-bundling/introduction.md).

# Introduction

Bitcoin’s UTXO model is reliable, but not built for speed or scale. Each UTXO (Unspent Transaction Output) is processed one by one. That works well for final settlement, but when volume spikes, it clogs the network, raises fees, and slows everything down.

UTXO Bundling, a core innovation in Bitcoin Thunderbolt, rewrites the rules, without touching Bitcoin’s base layer. It lets users transfer the spending rights of many UTXOs at once, securely and instantly, all off-chain. No merge. No movement. Just delegation, powered by cryptographic tweaks.

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