The image is the recipe and the frozen ingredients; the container is the meal actually cooking. Mix these two up and every Docker command feels random. Keep them straight and the whole tool suddenly reads like plain English.
Here is the whole distinction in one line: an image is a stored template, a container is a living instance created from that template. One image can start many containers at once, each independent. Deleting a container does not delete its image, and deleting an image is impossible while containers made from it still exist. Everything below is that idea, made practical with the handful of commands you will actually use daily.
An image is a packaged filesystem plus instructions: the operating system files, the application, its settings, and the command to start when a container launches. Images are built in layers - each step of the build adds a layer - which is why images sharing a base download and store their common layers only once.
docker pull nginx downloads an image without running anythingdocker images lists what your store holdsnginx:1.27, is the tag - the version label. No tag means latest, which simply means 'the default tag', not necessarily the newest releaseA container is an image brought to life: the engine takes the image, adds a thin writable layer on top, gives it a name, a network and resource limits, and starts the program the image specifies.
docker run -d --name web nginx starts one container from the nginx imagedocker ps lists running containers; docker ps -a includes the exited ones you forgot aboutContainers are meant to be disposable. docker stop web halts one; docker rm web deletes the container and its writable layer - including any data written inside it, which is exactly why the volumes page in this set matters. The image stays in the store, ready to start fresh containers.
docker rmi nginx removes the image itself, and Docker will refuse while any container created from it still exists - even an exited one. That refusal confuses beginners daily; now it will not confuse you.
Honest habit: the moment a container holds data you care about, that data belongs in a volume, not in the container's own layer.
In the video the first container is created from its image on screen - watch it once with this recipe-and-meal picture in mind.
▶️ Watch Full VideoNo. docker rm removes the container and its writable layer only. The image remains in your local store, and docker images will still list it. You only lose the image if you remove it separately with docker rmi, and Docker blocks that while containers from it exist.
Yes - that is the normal way Docker is used. Each container gets its own writable layer, name and network identity, all sharing the same read-only image underneath. Ten containers from one image cost little more disk than one.
Latest is just the default tag name applied when you do not specify one. It does not guarantee the newest version, and serious work pins an explicit version tag like nginx:1.27 so the software cannot change underneath you overnight.