How is a bit stored?

Excuse me, but could you please clarify for me how exactly a bit is stored in the world of cryptocurrency and finance? I understand that it's the smallest unit of data in computing, but I'm curious about its application and representation within the digital currency realm. Are bits stored physically on some form of hardware, or do they exist solely as digital constructs within a blockchain or other decentralized network? And how do these bits contribute to the security and integrity of transactions made on these networks?