Docker
Also written as container, containerization
A tool that packages an application with everything it needs to run into a portable 'container,' so it behaves the same on any machine.
Think of it like
Like packing an entire furnished room — furniture, outlets, wiring — into one shipping container that works identically no matter which truck or dock it lands at.
Junior or senior?
Junior sounds like
Has only worked with Docker images someone else built.
Senior sounds like
Has written a Dockerfile from scratch.
Ask them
“Have you written a Dockerfile from scratch, or mainly worked with images someone else built?”
Sounds like real experience
Describes a specific Dockerfile decision — a multi-stage build, a base image swap for size/security, a caching layer they restructured — and why it mattered.
Probe further if
Talks about running a container someone else built without describing anything they configured or changed themselves.