Blockchain, at its core, is a decentralized distributed database or ledger. So, how does the "blockchain ledger" keep records? In current blockchain projects, there are two mainstream accountingBlockchain, at its core, is a decentralized distributed database or ledger. So, how does the "blockchain ledger" keep records? In current blockchain projects, there are two mainstream accounting
What Is Unspent Transaction Output (UTXO)?
Blockchain, at its core, is a decentralized distributed database or ledger. So, how does the "blockchain ledger" keep records? In current blockchain projects, there are two mainstream accounting methods: The Account Balance Model (represented by Ethereum), and the Unspent Transaction Output (UTXO) Model (represented by Bitcoin). Understanding UTXO helps in comprehending the accounting logic behind Bitcoin's blockchain.
UTXO, which stands for Unspent Transaction Output, can be understood as the fundamental unit in Bitcoin transactions. For example, if Bob receives a Bitcoin payment and doesn't spend it, that Bitcoin becomes a UTXO. The UTXO model is similar to having a wallet where each UTXO is like a one-time-use paper bill. Each UTXO (paper bill) represents a specific amount of money, and by adding up all the UTXOs (paper bills), you can determine a user's balance.
In each transaction, whole integer multiples of UTXOs are used. For example, you can use 1 UTXO, 2 UTXOs, but you can't use fractions like 0.5 UTXO (similar to not being able to use half a paper bill). When a transaction occurs, the existing UTXOs (old paper bills) are consumed, and new UTXOs (new paper bills) are created. For example:In the morning, you go to buy coffee and a pastry, which costs $5. You hand the cashier a $10 bill. This $10 bill, represented as one UTXO, is given to the merchant. The merchant then gives you $5 in change, and at this point, you receive a new UTXO (a new $5 bill).
If this transaction occurs on a blockchain using the UTXO model, how would it operate? To understand this, we can abstract three transfer scenarios with examples, omitting miner fees for simplicity:
1.Two-Person Transactions
Let's assume Bob receives 10 BTC, so he has a UTXO of 10 BTC associated with his Bitcoin address. Now, Bob needs to transfer 2 BTC to Alice. In this case, the 10 BTC UTXO will be spent as a whole (the old paper bill is used up). 2 BTC (new paper bill) will be sent to Alice, and the remaining 8 BTC (new paper bill) will be returned to Bob as change. In other words, the original 10 BTC existed as a single UTXO, but during the transaction, this UTXO (the old paper bill) was destroyed and no longer exists. Instead, it was replaced by two new UTXOs (new paper bills): one belonging to Bob with a value of 8 BTC (which is the change returned to Bob), and the other belonging to Alice with a value of 2 BTC. In the future, Alice can use this UTXO as a balance to transfer to others.
If Alice wants to transfer those 2 BTC to Frank and to prevent Alice from double-spending those 2 BTC (which is akin to the well-known double-spending attack), miners need to verify that the UTXO has not been used in other transactions. If this UTXO has already been spent in a prior transaction, miners will reject the execution of this new transaction.
2. Multi-Party Transactions
Let's go through two examples to deepen our understanding. (1) One Address Transfers to Three Addresses (2) Three Addresses Transfer to One Address. Let's refer to these four addresses as A, B, C, and D. Scenario ① A transfers to B, C, and D. Scenario ② A, B, and C transfer to D. Initially, Address A has 10 BTC while B, C, and D have 0 BTC.
In scenario (1), Address A initially has one 10 BTC UTXO and wants to transfer 2 BTC to each of the addresses B, C, and D.
First, the original 10 BTC UTXO from A is entirely spent, and 2 BTC is sent to each of the addresses B, C, and D. The remaining 4 BTC is returned to A as change. At this point, the previous 10 BTC UTXO no longer exists and becomes four new UTXOs, one belonging to A valued at 4 BTC, and the other three belonging to B, C, and D, all valued at 2 BTC. After the transfer occurs, there is 1 UTXO of 4 BTC in Address A, 1 UTXO of 2 BTC in Address B, 1 UTXO of 2 BTC in Address C, and 1 UTXO of 2 BTC in Address D.
Now, let's simulate scenario (2), where A, B, and C each transfer 2 BTC to D.
The UTXO of 4 BTC at Address A will be spent as a whole, of which 2 BTC is transferred to D and 2 BTC is given as change to itself. The UTXO of 2 BTC in Address B is transferred to D, and the UTXO of 2 BTC in Address C is transferred to D. After the transfers have occurred, there will be 1 UTXO of 2 BTC in Address A, none at Address B, none at Address C, and 4 UTXOs of 2 BTC at Address D (1 of which is left over from the transfer happening in scenario ① and the rest are from scenario ②).
3. Two-Person Transaction, One Person has Multiple UTXOs
Suppose A has multiple UTXOs, which are 1 BTC UTXO, 2 BTC UTXO, 3 BTC UTXO, and 4 BTC UTXO, and B has no BTC. At this point, A needs to transfer 2.5 BTC to B. How does the UTXO model work?
At this point, the UTXO of 2 BTC in Address A will be transferred directly to B. The UTXO of 1 BTC will be spent as a whole, of which 0.5 BTC will be transferred to B, and 0.5 BTC will be given back as change. After the transfer, there are still 0.5 BTC UTXO, 3 BTC UTXO and 4 BTC UTXO in Address A. B has 2 BTC UTXO and 0.5 BTC UTXO.
In cryptocurrencies that utilize the UTXO model, if a user mistakenly enters an incorrect contract address, it is highly likely that the funds will be irrecoverable. This is because UTXOs do not store additional information about the transaction's outgoing state, and once a cryptocurrency transaction is completed, the corresponding UTXO no longer exists in the database. In essence, the system assumes that you have already spent the funds, and this action cannot be undone. Furthermore, if the contract address is incompatible or incorrect, it can lead to erroneous inputs, meaning the recipient cannot properly receive the cryptocurrency. As a result, it is very probable that the cryptocurrency will be unrecoverable.
We can see that: ① UTXOs record events rather than final states. ② Each UTXO represents a specific quantity of Bitcoin, and the sum of all UTXOs determines the account balance. ③ A UTXO is a Bitcoin transaction output. ④ A complete transaction consists of transaction outputs (senders) and transaction inputs (recipients). Transaction outputs can be referred to as Outputs, and transaction inputs can be referred to as Inputs. After a transaction is completed, any newly generated UTXOs are recorded in the Bitcoin ledger and can be used for further transactions. UTXOs, as the cornerstone of Bitcoin transactions, offer advantages such as security, privacy, and scalability. They serve as the foundational transaction framework for numerous blockchain projects.
The following tokens listed on MEXC use the UTXO model:
ADA, AE, AVAX, BCH, BCHA, BEAM, BHD, BSV, BTC, BTCV, BTM, BTM2, CHIA, CKB, DASH, DOGE, FIRO, HC, HNS, HYDRA, IOEX, KAS(KASPA), LBC, LBTC, LTC, MASS, PAC, PLCU, PSL, QTUM, RVN, SC, SYS, UT, WIT, XRD, XVG, ZEL, ZEN
If there is an error in transferring the cryptocurrency mentioned above, we will be unable to assist in recovering it. Please make sure to enter the correct deposit address before initiating any deposits!
Market Opportunity
Binance Coin Price(BNB)
$618.2
$618.2$618.2
USD
Binance Coin (BNB) Live Price Chart
Popular Articles
View More
Solana Bridge Guide: How to Bridge ETH to Solana Safely
If your crypto is sitting on Ethereum or BNB Chain while Solana's DeFi ecosystem keeps growing, you're leaving opportunities on the table. This guide breaks down everything you need to know about
USDC Scan: How to Track USDC Transactions on Ethereum, Polygon, and BNB Chain
When you send or receive USDC, do you know how to confirm the transaction actually went through? A USDC scan gives you the answer in seconds. This guide explains what a USDC scan is, how to use one
What Is the Next Bitcoin? Top Crypto Investments to Watch
Bitcoin's journey from under $1 to nearly $100,000 has created a generation of crypto millionaires. Now, investors worldwide are asking the same question: what is the next Bitcoin? With institutional
Hot Crypto Updates
View More
BNB (BNB) Latest Price: Fresh Market Updates
The crypto market changes minute by minute, and the latest BNB (BNB) price offers the most up-to-date snapshot of its value. In this article, we highlight the newest movements, fresh data from the
What is BASED-BSC (BASED-BSC)? An Introduction to Cryptocurrency
What Exactly is BASED-BSC (BASED-BSC)? BASED-BSC (BASED-BSC) is a blockchain-based cryptocurrency that powers the BNB Smart Chain (BSC) ecosystem focused on enhancing DeFi protocols, NFT
Trending News
View More
BNB Chain Welcomes xStocksFi – A New Era of 24/5 Tokenized U.S. Equity Trading
BNB Chain adds xStocksFi, giving DeFi traders 24/5 access to 50+ tokenized U.S. equities backed 1:1 by real assets, bridging TradFi and DeFi.
Bitcoin ETF Inflows Stay Strong As BNB Signals Breakout
The crypto market continues to show resilience as institutional capital quietly flows into Bitcoin. Major players like Fidelity and BlackRock continue to accumulate
Related Articles
View More
What is Stablecoin?
A stablecoin is a stable cryptocurrency backed by fiat currency, cryptocurrencies, or other assets like gold. Its purpose is to anchor the value to fiat currencies such as the US dollar or Euro. It co
What is ERC-20?
After years of development, Ethereum (ETH) has formed a complete ecosystem that allows developers to innovate and create complex DAPP (Decentralized Application) applications based on Ethereum. ERC-20
What is Blockchain?
Blockchain is not only confusing to newcomers in the cryptocurrency world, but many seasoned traders in the cryptocurrency community may also find it challenging to fully understand. However, after re
