What is Testnet and how does it work?

4 min read

Projects and cryptocurrencies are constantly implementing new functionalities and features. To make those new implementations successful, they must first ensure that they will not harm the functioning of the blockchain. This is where the work of the testnet begins.

A testnet is a crucial tool for cryptocurrency development. Through this type of network, developers can carry out tests without risking compromising the correct functioning of the main network. They are used by developers, programmers or simply users who want to experiment.

History of the Testnet

The beginnings of testnets date back to October 2010. Gavin Adresen, one of the Bitcoin developers, sent a patch to implement the new functionality accepted by Satoshi Nakamoto. This patch signified the start of the first testnet.

Bitcoin was not the only cryptocurrency to implement this system. This test network allowed any developer to implement and test different changes in the protocol of an application without damaging the main network. It was a breakthrough full of advantages.

Although it was a success, on February 3 of the following year the network was rebooted at the request of David Françoise who added a patch to the Bitcoin Core code. This new patch was called Testnet2.

Although it was expected that this version would improve on the first one, it turned out to have two major problems: first, the network increased the difficulty of mining so that getting the coin was a high cost and also, due to the high difficulty, many users began to sell Testnet coins as real BTCs.

The solution to this problem came on April 12, 2012 when Andresen restarted the network. This gave way to the new and latest Bitcoin testnet, the current Testnet3. It fixed the bugs of the first two testnets. Currently the third testnet is still active.


How does the Testnet work?

The testnet is an exact copy of the original blockchain of a cryptocurrency. Testnets were created for two fundamental purposes:

– Allow testing new implementations in cryptocurrency protocols without running the risk of affecting their performance.

– Allow developers to add protocols to applications at no cost.

Actions performed on a test network have no impact on the original blockchain. For copies of the blockchain, developers create what are known as near-identical genesis blocks. In this way the blocks and cryptocurrencies generated from the testnets are marked.

This separates the two blockchains and prevents coins from being transferred to the original blockchain. Thanks to this mechanism, coins from the testnet can never be transferred to the mainnet (original network). This solved the Testnet2 problem and prevented some users from profiting based on fraud.

Another problem solved was the mining difficulty. Current testnets are configured so that they do not increase the difficulty of mining cryptocurrencies. This causes the mining of cryptocurrencies in a testnet to be so easy that it cancels the value of the coins created.

Apart from the difficulty of mining and marking in genesis blocks, testnets are the same as their original network. This similarity must be almost exact to guarantee that if a new implementation works on the testnet, it will also work on the mainnet.

Do you know what Kusama is? Polkadot’s tesnet is a great example that will help you understand how test networks work.