What is Proof of Work?

Whitney Anderson
Whitney Anderson
Technology Writer
Last updated: May 20, 2024
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Proof of work (PoW) is a basic idea in blockchain technology for decentralized consensus across distributed networks. It is the main mechanism that allows peer-to-peer transactions between parties who don’t know each other and have no reason to trust one another in cryptocurrencies or other systems based on blockchains.

In this context, what does proof of work mean? It is a way to form an agreement among network participants about transaction validity and ledger state when there is no trusted central party.

The process requires miners—a term referring specifically to those who take part in mining—to use computational resources to solve complex cryptographic equations called hash functions as a method of verifying transactions and creating new blocks as part of the blockchain. These puzzles are solved by running dedicated software programs on specialized computer systems known as nodes.

Initially designed to defend against spam and denial-of-service (DoS) attacks within centralized systems, digital tokens were introduced with the reusable proof-of-work concept using 160-bit secure hash algorithm 1 (SHA-1) by US software developer Hal Finney in 2004.

Satoshi Nakamoto, the author of the Bitcoin cryptocurrency system which he published under a pseudonym, adopted it as an underlying consensus mechanism when launching bitcoins into circulation around January 2009; since then PoW has become synonymous with security/ decentralization within the crypto space powering many major public ledgers.

XPS.NET Explains Proof Of Work

XPS.NET Explains Proof Of Work

A blockchain is an electronic record that keeps all transactions made digitally on a peer-to-peer basis throughout its network. In cases where cryptocurrencies such as Bitcoin are utilized, peers may perform P2P transactions although they lack trust or knowledge about one another and lack any reliable intermediaries like banks therefore considered “trustless”.

To make sure these transactions are decentralized and “trustless”, while still being safe from errors or fraud; consensus mechanisms like proof-of-work come into play for securing functions on blockchain networks. Without a central authority, PoW acts as an agreement between network participants on transaction validity and the state of a distributed ledger.

If you want to know what proof of work means, think about a mining task verifying transactions within a block. A cryptographic puzzle associated with that block must be solved before the miner can add it to the blockchain by becoming the first to complete this computation. In return for using computational resources to do so they receive some amount (e.g., Bitcoin) of newly minted units as well as a share in transaction fees which is called reward; every four years ‘halving’ takes place reducing block rewards by half thereby controlling cryptocurrency supply.

One disadvantage is its energy consumption since large computer networks continuously run through numerous cryptographic equations; thus engineers have come up with other types of consensus mechanisms for verifying transactions like proof-of-stake (PoS), proof-of-authority (PoA), Practical Byzantine Fault Tolerance (PBFT)

How Does Proof of Work (PoW) Work?

To form one data structure, blocks are needed where each carries information regarding the sender’s account number, the recipient’s account number, the amount sent, date & time, etc, both encrypted into a header. This header containing details about every single transaction made within that particular block represents an encrypted hexadecimal number created by the hashing function of the blockchain itself.

Every block’s hash is used in the next block’s hash, creating a chain of blocks that are permanent and cannot be modified or tampered with. The PoW blockchain security and immutability are built upon this string of interlinked hashes, where any alteration to any previous block will render all subsequent blocks invalid.

Proof of Work and Mining

At the closing of each block, the hash must be confirmed before a new one can be created. The hash contains a nonce (short for “number used once”), which is simply a series of numbers. Miners generate their new-block’s-hash value using computational resources.

The network picks a target hash value — this is just a mathematical formula result converted into a hexadecimal number. The mining difficulty is determined by this target hash value; it dictates how hard miners need to work to find an acceptable hash.

Proof of Work and Mining
Source: Hacken.io

Miners have to generate a hash value less than the target hash value if they want their new block creation attempt to succeed. If the miner’s hash value is greater than what the network set as its goal (target), then the mining program adds 1 to the nonce and computes another one. And so it continues until the miner comes across such a satisfactory hash value according to set criteria. Once found out, solving miners broadcasts solutions throughout networк.

Other network participants confirm whether the given proposed hash value is indeed correct and meets the required conditions after which the majority of nodes agree with one another hence attaining consensus among themselves; thus a successful miner is awarded the right to add a new block into the chain plus receiving the associated reward for having done so.

Mining Difficulty

Blockchain difficulty is determined by the amount of work needed to solve cryptographic problems and add new secure blocks to a blockchain. It also helps keep the system stable by protecting against outside interference like when the hash rate fluctuates due to changes in total computational power. In Bitcoin, block time usually takes roughly 10 minutes on average but this can sometimes change depending on different factors.

Sometimes referred to as ‘block generation rate’, mining difficulty acts as an independent regulator here ensuring a stable rate regardless of any fluctuation hash rate since this could lead to frequent changes in creation times which might disrupt the whole system thus making it difficult to maintain constant flow events within such an environment.

When more miners start competing to solve the same equations – that’s when the hash rate goes up – puzzles become harder hence the difficulty increases proportionately; however if the opposite happens where few people involve themselves in solving these problems – that’s when hash rate decreases – it becomes easier for a smaller number of miners to generate blocks at desired pace so in order not upset things where they are supposed to be kept, reduced puzzle complexity level should follow suit.

In other words, the value of the target hash is adjusted based on how easy or difficult it should be for the miners to find a valid one that can create a new block according to set rules.

Miners in the Proof of Work (PoW)

The primary task of miners within the PoW system is to validate and add new blocks to the PoW blockchain. They dedicate a lot of computational resources to solving cryptographic puzzles of the network and for that, they get rewarded with newly created units of cryptocurrencies as well as transaction fees.

With blockchain networks like Bitcoin growing bigger and more popular attracting numerous miners, it has become harder for individual miners to win the race in solving these cryptographic puzzles. Consequently, miners have gone from using single computer systems to setting up large-scale operations often by forming or joining mining pools which increase their chances of receiving rewards by combining computational power.

Full Node Operators in PoW

Apart from miners, full node operators play an important role towards achieving security and decentralization within PoW blockchain networks. Full nodes keep complete copies of entire blockchains without engaging in any mining activity.

These types of nodes are responsible for authenticating blocks and transactions; ensuring they abide by network rules and consensus protocols thus verifying their genuineness. If there is disruption or failure on the blockchain, full nodes allow it to be restored since they always possess an up-to-date copy of all ledgers.

Proof-of-Work Versus Proof-of-Stake

In contrast to proof-of-work which uses computational power and energy consumption to reach consensus; proof-of-stake (PoS) seeks similar goals but with reduced energy usage coupled with higher scalability. In a PoS network validators are chosen depending on how much cryptocurrency they own and are willing to “stake” i.e., lockup as collateral on that particular blockchain.

PoS is environmentally friendly and more energy efficient than PoW in a sense that it does not require validators to undertake energy-intensive computation processes towards solving cryptographic puzzles. Instead, stakers receive part of transaction fees as a reward without earning new coins as done through the mining process under the Proof Of Work model.

PoS blockchains can run much faster block creation rates compared to PoW chains by selecting validators based on their staked cryptocurrency holdings rather than waiting for miners to solve equations. For example, the average block time of Ethereum representing its block creation rate is around 12 seconds after transitioning into PoS while that of Bitcoin is 10 minutes under the PoW design. This higher throughput may enable PoS networks to achieve greater scalability and process more transactions per second.

Here’s how proof-of-work differs from proof-of-stake:

Aspect | Proof of Work (PoW) | Proof of Stake (PoS)

Consensus Mechanism | Requires miners to solve cryptographic puzzles through computational work | Selects validators based on the amount of cryptocurrency they hold and are willing to stake

Energy Consumption | High relies on intensive computational power and consumes significant energy | Lower, as it doesn’t require extensive computational work

Validators | Miners | Stakers

Reward System | Miners receive newly minted coins as well as transaction fees | Validators receive a share of transaction fees as rewards

Scalability | Usually less due to slower block creation rates | More due to faster block creation rates Cryptocurrencies that Use Proof of Work Some of the major cryptocurrencies that use PoW as their consensus mechanism are listed below: 

Cryptocurrencies Based on Proof of Work

Many well-known cryptocurrencies employ PoW as their consensus mechanism, viewing it as the only way to keep the security and fairness of their fundamental blockchain networks within reach. Here are some of the primary cryptocurrencies that use PoW:

  • Bitcoin (BTC)
  • Dogecoin (DOGE)
  • Litecoin (LTC)
  • Monero (XMR)
  • Nervos Network (CKB)

Bitcoin is still considered one of the most typical examples where the proof-of-work concept functions properly being the first cryptocurrency ever invented.

PoW Example: Bitcoin Blockchain

The PoW consensus mechanism was initially implemented by the Bitcoin blockchain for transaction validation and block creation, which remained a widely accepted method even after its first invention.

On a Bitcoin blockchain, transactions are grouped into blocks, which are then validated by PoW. Afterwards, a hash value is generated for that block using an algorithm. The SHA-256 algorithm is used in bitcoins and this type always produces 64-character hashes.

Miners compete to create a hash of the block that is less than or equal to the current target block hash. The target block hash is computed by dividing the maximum allowed value for a block’s hash by the current mining difficulty. The first miner who successfully does this earns the right to add a batch of transactions to the public ledger. They are also given new bitcoins as a reward for creating blocks and some transaction fees. This verification procedure strengthens network security and protects many activities that involve digital currencies like safe coin transfers. Finally, such undertakings help foster worldwide assurance of recorded ownership claims over various assets exchanged within Bitcoin communities.

The number of newly minted bitcoins awarded to successful miners—referred to as block rewards—is designed to halve roughly every four years during an event known as “the Halving.” The next halving will occur in April 2024 when the block reward drops from 6.25 BTC to 3.125 BTC. After every 210,000 blocks are mined over time this way controls the supply of bitcoins available into circulation around the world thereby ensuring scarcity remains intact while increasing its value proposition over time through various other means apart from just limiting the number produced each year through mining activity alone.

Pros and Cons of Proof of Work

Like any other technology, proof of work also has its advantages and disadvantages. Below are some pros and cons of the POW consensus mechanism:


Security against malicious attacks: It’s hard for ill-intentioned people to take control when they would have to do so much computationally expensive work for their changes or additions to be accepted by the rest nodes on the network.

Miners spread all over the world: This decentralized approach where miners from different countries participate in securing a blockchain-based system enhances its security while at the same time making it more resilient against failure as well due to geographical distribution among other factors.

Mining accessibility: Theoretically, rewards can be earned by anyone who mines with enough computational resources.


Energy-intensive Feature: The most complained aspect about PoW is the amount of energy it consumes. The mining process involves solving complex puzzles and verifying transactions using a lot of computational power which in turn uses up massive amounts of electricity hence raising concerns over the environmental friendliness of PoW blockchains.

Scalability Limitations: For proof-of-work networks, the time taken to verify and add new blocks may affect scalability and transaction throughput across the whole system. When more transactions are made, it may overwhelm the processing capabilities of those working with Proof-of-Work chains thereby extending confirmation periods as well as creating potential bottlenecks.

Specific Hardware Prerequisite: With time, minefields within PoW have become specialized necessitating the need for Application-Specific Integrated Circuits (ASICs) or Graphic Processing Units (GPUs). These devices are optimized towards mining activity making them costly such that few people can afford them, hence they act as an entry barrier into this field while contributing towards the centralization of mining power.

Centralizing Propensity: Although designed to be decentralized, Proof-of-work networks can see large pools being formed where the majority hash rate comes from few participants who might not even follow rules strictly set by creators thus undermining the true nature behind decentralization. As a result, this compromises security levels across the network as well as overall integrity.

51% Attacks: In case one organization controls over 50% total hash rate on any given blockchain using the PoW consensus mechanism then it could execute a 51% attack which allows it to tamper with the record-keeping system known as blockchain so that it can do double spending among other malicious actions. However, these types of attacks are resource-demanding, thus economically unfeasible but remain only a theoretical threat under the PoW protocol.

Bottom Line

Proof of work is an innovative consensus algorithm that ensures secure trustless peer-to-peer transactions within blockchain networks. Despite some disadvantages like high consumption rates and scalability problems; PoW continues supporting major cryptocurrencies thereby influencing Defi in future through decentralization of finance across digital economies.

Currently, there are other methods such as PoS which stands for Proof-of-Stake being introduced alongside various forms of consensus mechanisms due to the evolving nature of blockchain technology and its associated implications on proof-of-work. Nevertheless, foundational concepts together with novel ideas brought about by this system will always form part of any decentralized network based on blocks.


What is proof of work in short?

PoW is a mechanism used by miners to validate transactions and create new blocks within the blockchain. It requires them to solve complex cryptographic puzzles.

What’s the difference between PoW and PoS?

Proof of stake (PoS) systems select validators based on the amount of cryptocurrency they hold and are willing to risk, while proof of work (PoW) miners must utilize computational resources to solve cryptographic puzzles.

Can you give me an example of what counts as “proof” under POW rules?

Bitcoin is often cited when discussing examples where people have used different kinds of calculations or processes as proof under this protocol type. 

Is Bitcoin using proof-of-work?

Yes, Bitcoin itself was created with these types of algorithms at its core so that transaction validation could be achieved alongside block creation security features.

What is the role of mining difficulty in PoW?

Mining difficulty is a parameter that sets how difficult it is for miners to solve the cryptographic puzzles necessary to form new blocks. This adjusts flexibly to keep up an even pace of block creation while still protecting the security of the network.

What are some key benefits of proof of work?

Some major advantages are resistance against malicious assaults, distributed network systems involving miners throughout different regions and countries as well as any person who has computational resources being able to take part in mining.

What are some main drawbacks associated with proof-of-work algorithms?

The main disadvantages include heavy energy consumption; low transaction throughput or scalability limits; and the formation of big mining pools leading towards possible centralization risks.

How does PoW ensure decentralization and security?

By allowing validation transactions via anyone having computational resources, this method guarantees decentralization. It also achieves security by making it expensive for attackers trying to gain control over networks through computation power alone or other means like double spending attacks which require significant amounts of mined coins.

What is a 51% attack in the context of PoW?

When one entity possesses more than half the total hash rate on the network then they can potentially manipulate blockchain history i.e. perform double spending, among other things.

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Whitney Anderson
Whitney Anderson
Whitney Anderson is a dynamic technology writer and content creator known for her quick learning and strong interpersonal skills. With a passion for community service and travel, she excels in crafting engaging tech content and leading diverse teams. Whitney is eager to bring her tech expertise and creativity to make a significant impact in your organization.

Why Trust Us

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