In a typical virtualization setup, a hypervisor (like Xen or Hyper-V) is used to run multiple virtual machines on a single physical server.

This is the standard approach you will find in many on-premise environments as well as the backends of cloud platforms.

Containers operate differently.

They dont need separate operating systems. Instead, they all share the same operating system kernel, which is the core part of the OS that manages resources like CPU, memory, and networking.

This approach is called OS-level virtualization.

It is what makes containers much lighter and faster than virtual machines, allowing them to start in less than a second.

In contrast, virtual machines may take anywhere from 30 seconds to 2 minutes to boot, depending on the operating system and configuration.

There is also technology called microVMs (for example, AWS Firecracker). They sit between virtual machines and containers. It offers strong isolation of VMs while being almost as lightweight and fast as containers.

In the next lessons, we will cover the core concepts you need to build a strong understanding of containers.