Blockchain technology has proven itself to be a revolutionary actor across a wide spectrum of industries. Unfortunately, these technologies don't happen overnight. There is painstaking work that must take place or even simple projects to come to fruition.
This is where the mainnet and testnet enter the picture.
Learn more about it here:
https://blog.kucoin.com/what-happens-when-a-coin-goes-mainnet-sk-btMainnet(main network) is nothing but the main blockchain where actual transactions take place in the distributed ledger and the native cryptocurrencies hold real economic value.
Mainnet is where the execution of real transactions takes place within the network. It is stored on the blockchain and is called the final product that is open for the public to use.