What is a Testnet?

By
Jeff Whitley
January 7, 2025
5
min read

We are all entitled to a reliable system that functions properly. If this is to be achieved, then a series of tests should be conducted so that the system in question functions correctly. There is a type of software that cryptocurrencies use for their systems to carry out such experiments, and that software is called a ‘testnet.’

What is it?

A testnet is a software that is identical to the software that is being used by a cryptocurrency. They are basically an alternative Bitcoin blockchain that is used primarily for testing purposes.

Because testnets are designed as a means to experiment with new ideas without causing any disruption to the main cryptocurrency software, the coins attached to the testnet are separate entities from the genuine bitcoins and are lacking any real value. This framework allows application developers and/or bitcoin testers to experiment with the advantage of not having to worry about causing any changes to the real blockchain.

Thus far, there have been three generations of testnets. ‘Testnet2’ was the first testnet reset done with a different genesis block on account of people beginning to trade testnet coins for legit money. ‘Testnet3’ is the test network that is currently running.

Testnet3 was first introduced with the 0.7 release and it brought in a third genesis block, established a new rule to avoid the “difficulty used to be too high, now it is too low, and transactions are taking too long to verify” issue, and contains blocks with edge-case transactions that are constructed as a way to test the compatibility of implementation.

As previously stated, one of the more notable reasons as to why testnet exists is for developers to perform specific tests. To elaborate, when developers at Bitcoin wish to introduce new modifications to the protocol – such as Segregated Witness (SegWit) – then they have to make absolutely sure that the concept is meticulously tested first and foremost. As testnet is an alternative version of the actual chain, this experiment can be carried out rather easily.

Functions

The testnet system serves a wide variety of crucial functions, some of which include:

  • Constant Development

Due to blockchain technology being a structure that is still technically in its infancy, it requires a great amount of testing and development is needed if it wants to achieve mainstream adoption and usage.

For example, one of the main issues with blockchain that is actively being addressed by the community is scalability. To remedy this, rigorous research and expansion are being conducted by a wide range of projects to enhance the capability of blockchain processing additional transactions. If they want to improve blockchain’s capabilities as frequently as possible, then numerous testings on smart contract functionality, transactions, and the mining procedure must be undertaken.

Ultimately, the testnet serves as something of a simulation on how the real chain protocol would operate under real-world conditions.

  • Prevent Disturbances

By now, it should be apparent that a testnet provides testers and developers a platform to experiment on potential features and functions for the protocol without the worry of disrupting anything on the primary blockchain.

Conducting these tests on the main chain would evidently be a troublesome task since the complex interactions between components within the protocol could jeopardize the network or even break the chain. This would inevitably create massive disruptions to the blockchain and could sabotage the entirety of the protocol. This is chiefly why it is a common practice for projects to run a prototype on a testnet before launching it so that technical details can essentially be ironed out and then ensure that everything is properly in order.

  • Free Testing

For blockchains that approve of smart contract functionality, native coins are permitted to be spent in order to carry out smart contract transactions.

For example, Ether (ETH) is needed to pay for the calculations that occur within the Ethereum blockchain (similarly referred to as ‘Ethereum Virtual Machine’). Testnets provide a reliable experimental ground for developers who are interested in designing applications on the chain or testing out certain functionalities without having to spend any real currencies.

In hindsight, it would be extremely costly for developers to test out their application features or run experiments on the main blockchain, seeing as how they would need to purchase coins of real value in bulk.

Mainnet: what’s the difference?

If you are someone who has already done their fair share of research on the subject of testnets, chances are pretty good that you have come across the term ‘mainnet’ at some point. Upon first glance, you might assume that mainnets and testnets essentially mean the same thing or are exactly the same thing, however, there are key differences between the two that can be cleared up with a basic breakdown.

A mainnet – a shortened version of ‘main network’ – is defined as being the original and currently functioning blockchain where legit transactions are carried out in the distributed ledger. In addition, the native digital currencies possess authentic economic value.

To sum up, the mainnet pertains to the actual open-source blockchain itself that is verifiable and accessible by the public. It orchestrates the functionality of executing real transactions within the network which is kept on the chain and is referred to as the “end product” that is open for public use.

Like testnets, a mainnet serves a variety of functions. Two of these include:

  • Proof of Development

A mainnet acts as verifiable proof that a project has developed a fully functional and working blockchain where legitimate transactions can occur. Acquiring a mainnet is a tell-tale sign that the project has now gone live and is in technical progress.

  • Credibility

A project with a mainnet undoubtedly retains more credibility than a project that does not have one. Due to the fact that a mainnet is a concrete, functioning protocol, all of the transactions are live and any participant can transact with another participant with the native coins belonging to the chain.

When it comes down to it, there are two key differences between testnets and mainnets: the network ID and the genesis block. A network ID is basically an identifier for a network, similar to an ID card that represents one’s identity, and a genesis block is the very first block in the chain that represents the starting point. Since both the mainnet and the tesnet operate as different networks, they have different genesis blocks, though the content of the block may be the same.

Conclusion

Overall, testnets are a vital component for the development of a cryptocurrency. They aid in ironing out the details and repairing any potential damages without placing a strain on the already-existing blockchain, thereby making the act of experimenting with conceptual designs both trustworthy and secure.