Docker Tutorial — Docker Objects
Docker manages four primary types of objects. Understanding them gives you a complete picture of what Docker tracks and controls.
The Four Docker Objects
| Object | What It Is | Command |
|---|---|---|
| Images | Read-only templates for creating containers | docker image ls |
| Containers | Running instances of images | docker container ls |
| Volumes | Persistent data storage managed by Docker | docker volume ls |
| Networks | Communication channels between containers | docker network ls |
See All Objects
# Images on your system
$ docker image ls
REPOSITORY TAG IMAGE ID SIZE
nginx latest a1b2c3d4e5f6 187MB
ubuntu 22.04 f6e5d4c3b2a1 77.8MB
# Running containers
$ docker container ls
CONTAINER ID IMAGE STATUS NAMES
a1b2c3d4e5f6 nginx Up 5 min web1
# Volumes
$ docker volume ls
DRIVER VOLUME NAME
local postgres_data
# Networks
$ docker network ls
NETWORK ID NAME DRIVER SCOPE
a1b2c3d4e5f6 bridge bridge local
f6e5d4c3b2a1 host host local
1a2b3c4d5e6f none null local
Quick Reference
docker image ls → list images
docker container ls → list containers (-a for all)
docker volume ls → list volumes
docker network ls → list networks
docker system df → disk usage by object type
