juniorDocker
What is Docker and how does it differ from a Virtual Machine?
Updated Apr 28, 2026
Short answer
Docker is a containerization platform that shares the host OS kernel, making it lightweight compared to VMs which require a full guest OS.
Deep explanation
Docker leverages Linux namespaces and cgroups to provide isolation. Unlike VMs, there is no hypervisor layer overhead, allowing for near-native performance and rapid startup times.
Real-world example
A developer wants to ensure their app runs exactly the same on their laptop as it does on a colleague's machine.
Common mistakes
- Confusing 'EXPOSE' with port publishing ('-p').
Follow-up questions
- What is a 'layer' in Docker?