What is the difference between a Docker image and a container?

An image is a read-only template containing an application and its dependencies; a container is a running, isolated instance created from that image.

How do I map host port 6000 to port 6379 in a Docker container?

Use the command `docker run -p 6000:6379 `, which forwards traffic from host port 6000 to container port 6379.

What is the difference between docker run and docker start?

`docker run` creates and starts a new container from an image, while `docker start` restarts an existing stopped container.

Free online course Docker for beginners

Duration of the online course: 2 hours and 46 minutes

New

Deploy apps faster with a free Docker course: learn images vs containers, port mapping, volumes, and Compose so your projects run anywhere.

In this free course, learn about

Core Docker concepts: images, containers, layers, registries, and basic CLI workflow
Key differences between Docker images and containers and how lifecycle/state is managed
Docker vs VMs: what Docker virtualizes and implications for isolation and performance
Port mapping fundamentals, e.g., bind host 6000 to container 6379 (6000:6379)
How Docker Compose enables service-to-service DNS by auto-creating a default network
Data persistence with volumes; why named volumes are recommended for production
When to use docker run vs docker start and how they differ in creating vs restarting

About the free online course

Docker has become a standard tool for developers and IT teams who want reliable environments, faster releases, and fewer it works on my machine surprises. In this free online course, you will build a clear, practical foundation to understand what Docker is really doing under the hood and how to use it confidently in day-to-day projects. Instead of treating containers like magic, you will learn the core concepts that help you troubleshoot issues, share projects smoothly, and ship applications with consistency across laptops, servers, and cloud platforms.

You will start by connecting the big picture to hands-on practice: what a container is, what an image is, and why the difference matters when you build, run, update, or distribute an application. From there, you will see how Docker compares to virtual machines, what is actually being virtualized, and why containers are lightweight while still providing the isolation teams need. These fundamentals make it easier to choose the right approach for local development, testing, and deployment workflows.

Real projects also depend on networking and connectivity. You will learn how port mapping works so you can expose services running inside containers to your host machine and other systems in a predictable way. You will also understand how Docker Compose helps multi-service setups work together by creating the necessary network layer so services can communicate using service names instead of hard-coded IP addresses. This is especially useful when developing stacks such as web apps connected to databases, caches, or message queues.

Because containers are designed to be disposable, managing data correctly is essential. You will explore persistence strategies and understand why choosing the recommended production-friendly volume type makes your data safer and your environments easier to maintain. Finally, you will clarify the difference between running a new container and starting an existing one, a small distinction that often causes confusion when restarting apps, applying updates, or recovering from failures.

By the end, you will be able to reason about Docker behavior, read common commands with confidence, and set up cleaner local environments that match real deployment needs. If you are aiming for a developer, DevOps, or cloud role, these skills translate directly into more efficient teamwork and smoother delivery pipelines.

Course content

Video class: Docker Tutorial for Beginners [FULL COURSE in 3 Hours] 2h46m
Exercise: Image vs Container: What is the key difference?
Exercise: Docker vs VM: What does Docker virtualize?
Exercise: Port mapping: How do you bind host 6000 to container 6379?
Exercise: Docker Compose: What does it auto-create so services reach each other by name?
Exercise: Persistence: Which volume type is recommended for production?
Exercise: docker run vs docker start: What is the difference?

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Explore free online Docker courses with certificates and learn containerization, image management, Docker Compose, networking, security, and deployment. Build practical DevOps skills through beginner-friendly lessons and hands-on training, then earn a certificate to showcase your Docker knowledge and advance your career.