How does running a node work?

Could you elaborate on the process of running a node in the cryptocurrency ecosystem? As a financial practitioner, I'm curious to understand the technical aspects and how it contributes to the overall network. Specifically, what are the requirements for setting up a node? What kind of hardware and software do I need? Additionally, what are the responsibilities and benefits of running a node? How does it impact the security, scalability, and decentralization of the network? Clarifying these points would help me gain a deeper understanding of the role of nodes in cryptocurrency systems.