<p>Balances in Bitcoin are stored in Unspent Transaction Outputs <a href="/questions/tagged/utxo" class="post-tag" title="show questions tagged &#39;utxo&#39;" rel="tag">utxo</a>. UTXO can be used as inputs when a transaction is created. They can only be spent completely, while the resulting transaction creates new ones in the process, redistributing the balance to the recipients of the transaction. <em>Spent transactions</em> refers to Transaction Outputs that have been expended.</p>

CC BY-SA 3.0
2015-09-08T03:23:25.167Z
@green Note that this way of saving disk space as Satoshi described it is not actually used as such. Bitcoin simply keeps a separate UTXO database and basically only keeps the original blocks (with the actual transactions) to be able to upload them to any per asking for them. Recent Bitcoin Core versions do have the ability to simply completely delete really old blocks. This is called purging.
Jannes
CC BY-SA 3.0
2015-08-31T09:52:47.990Z
2015-08-31T09:52:47.990Z
Murch
<p><a href="https://bitcoin.org/bitcoin.pdf" rel="nofollow">Satoshi's paper</a> says:</p>

<blockquote>
  <p>Once the latest transaction in a coin is buried under enough blocks,
  the spent transactions before it can be discarded to save disk space.</p>
</blockquote>

<p>What are <em>spent transactions</em>?</p>

<transactions><utxo><storage-footprint><pruning>
What are spent transactions?
Green
# What are spent transactions?

(Asked by: username_0 on 2015-08-31)

[Satoshi's paper](https://bitcoin.org/bitcoin.pdf) says:

> Once the latest transaction in a coin is buried under enough blocks,
> the spent transactions before it can be discarded to save disk space.

What are *spent transactions*?

**Tags:** transactions, utxo, storage-footprint, pruning


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## 1 answers

### Answer by username_1 on 2015-08-31. Score: 2

Balances in Bitcoin are stored in Unspent Transaction Outputs [utxo](/questions/tagged/utxo "show questions tagged 'utxo'"). UTXO can be used as inputs when a transaction is created. They can only be spent completely, while the resulting transaction creates new ones in the process, redistributing the balance to the recipients of the transaction. *Spent transactions* refers to Transaction Outputs that have been expended.

> **Comments:**
> **username_2**: @username_0 Note that this way of saving disk space as Satoshi described it is not actually used as such. Bitcoin simply keeps a separate UTXO database and basically only keeps the original blocks (with the actual transactions) to be able to upload them to any per asking for them. Recent Bitcoin Core versions do have the ability to simply completely delete really old blocks. This is called purging.  

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