Three mini-questions about Docker: what is Docker, Docker Compose, Docker Image?

Docker is a platform for building, shipping, and running applications in isolated containers. Containers allow you to package an application with all its dependencies, ensuring consistent operation across different environments.

Docker Image is a template or snapshot from which a container is created. An image contains everything needed to run an application: code, libraries, configurations.

Docker Compose is a tool for defining and running multi-container Docker applications. Using a docker-compose.yml file, you can describe multiple services, their relationships, networks, and volumes, and then start them with a single command.

Example docker-compose.yml for a web application and database:

version: '3'
services:
  web:
    image: myapp:latest
    ports:
      - "80:80"
    depends_on:
      - db
  db:
    image: postgres:13
    environment:
      POSTGRES_PASSWORD: example

This launches two containers: an application and a database, linked together.