# Introduction to Docker Docker is a containerization platform that packages apps and their dependencies into isolated containers. ## Key Concepts - **Container**: Lightweight, standalone environment for your app. - **Image**: A snapshot of the container’s filesystem. - **Dockerfile**: Defines how to build your container image.
## Example Dockerfile ```dockerfile FROM node:16-alpine WORKDIR /app COPY package*.json ./ RUN npm install COPY . . EXPOSE 3000 CMD ["npm", "start"] ``` Containers ensure consistency across environments, enabling smooth deployments and reducing “it works on my machine” issues.