What’s the Bigger Picture of IT Infrastructure?

First of all, Happy "Vinayagar Chaturthi" ! 🙏

I want to ask the experienced sysadmins about the whole IT infrastructure.

Just imagine a student comes to you. He doesn't really know anything about IT infrastructure, or how a business actually works.

He asks you…

“What is IT infrastructure? Why does a company need it? How does it actually help the business? What does a system administrator do? And can you explain your company's whole IT infrastructure to me?”

Then he keeps asking questions,

Why do we need servers? Why do we need a network? Why do we need Active Directory Why DNS and DHCP? Why a firewall? Why backups? Why user accounts and permissions? Why security? Why monitoring?

And finally,

“Okay, but how does all of this actually help the company make and run its business?” (That's the part I'm really interested in)

As a sysadmin, how would you explain the whole thing ?

Not just giving definitions of each technology, but explaining how everything connects together and supports the actual business.

For example, take a manufacturing company. There are employees, computers, applications, ERP, files, databases, internet, servers, network devices, security systems, backups, etc.

How does all of this come together to keep the business running?

I'm asking because I'm new to system administration. I can learn individual technologies, but sometimes I feel like understanding each technology separately isn't enough. I want to understand the bigger picture of why these things exist and how they work together.

Just like,

“This is what IT infrastructure is, this is why the business needs it, and this is what a sysadmin does.”

I'd genuinely like to hear how experienced sysadmins would explain this.