Most blockchains are completely open source software and anyone can see the code. Being able to view the source allows auditors to examine cryptocurrencies like Bitcoin for security. The fact that the code is visible to everyone also means that there is no real authority over who controls Bitcoin's code or how it is regulated. Therefore, anyone can suggest changes or upgrades to the system. Bitcoin can be updated if the majority of network users agree that with the upgrade the new version of the code is solid and valuable.