The software that allows the users to interact and connect with the Bitcoin network is called Bitcoin Core. The founder of Bitcoin, Satoshi Nakamoto, founded Bitcoin Core in 2009.
It is an open-source and free project relying on contributors across the globe. These contributors are also provided with outside grants by people who wish to support the development of Bitcoin. Users can easily download and run Bitcoin Core or use a packaged node software that generally has Bitcoin Core in it.
Users can become independent nodes on the Bitcoin network by running Bitcoin Core. This provides the users with the independence to audit and verify transactions appearing on the blockchain, thereby making the entire process trustless. Running your own Bitcoin Core adds another layer of security while using Bitcoin, since the need to broadcast your information to third parties is no longer required.