Before Understanding What Containers Are, Let's First Understand Why We Need Them
Imagine a developer working on a Windows machine. They write some code, push it to Git, and then the ops team pulls the code onto a server. Suddenly — the code that worked perfectly on the developer’s machine doesn’t work on the server.
The developer says:
"It works on my machine 🙃"
Why does this happen?
Because the environments are different — there are dependency inconsistencies.
Example:
A developer builds a Node.js application using Node 22, but the server has Node 18 installed.
Result? The application breaks.
Another big problem containers solve:
When a new developer joins the team, they often spend hours or days setting up the correct environment (installing libraries, setting versions, fixing OS-specific issues).
This setup is tedious and varies across different machines.
A container provides a consistent environment for developing, shipping, and running applications — no matter where it runs.
Docker is a platform that makes it easy to create, deploy, and run containers.