Virtualization lets one physical computer pretend to be many. The operating systems inside don't know they're sharing hardware—and that productive deception changed everything about how we build infrastructure.
A virtual machine is a lie that software believes—an operating system convinced it's running on real hardware when it's actually running inside another computer. That lie turns out to be extraordinarily useful.
A hypervisor's job is to lie—convincingly telling each virtual machine it owns hardware that doesn't exist, while secretly sharing one physical host among many.
Type 1 hypervisors replace the operating system. Type 2 hypervisors run on top of one. That single architectural choice determines performance, security, and when you'd use each.
VMs virtualize hardware; containers virtualize the operating system. That single difference explains everything else—why containers are tiny and fast, why VMs provide stronger isolation, and when each actually makes sense.
Docker containers share the host OS kernel instead of virtualizing entire machines—making them start in seconds, consume megabytes instead of gigabytes, and run identically everywhere.
Kubernetes is a promise-keeper for containers—you declare what you want running, and it relentlessly makes reality match your declaration.
Serverless computing is a deal: you give up control over how your code runs in exchange for never thinking about servers again. Here's when that trade makes sense.
FaaS inverts the relationship between code and infrastructure—you write functions, and servers materialize around them exactly when needed, then vanish.
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