DevOps: What is container registry?

1# Docker Hub
2docker login
3docker build -t myuser/myapp:1.0 .
4docker push myuser/myapp:1.0
5docker pull myuser/myapp:1.0
6
7# GitHub Container Registry
8docker build -t ghcr.io/myuser/myapp:1.0 .
9docker push ghcr.io/myuser/myapp:1.0
10
11# AWS ECR
12aws ecr create-repository --repository-name myapp
13aws ecr get-login-password --region us-west-2 | docker login --username AWS --password-stdin 123456789.dkr.ecr.us-west-2.amazonaws.com
14docker build -t myapp .
15docker tag myapp:latest 123456789.dkr.ecr.us-west-2.amazonaws.com/myapp:latest
16docker push 123456789.dkr.ecr.us-west-2.amazonaws.com/myapp:latest
17
18# Google Container Registry
19docker build -t gcr.io/my-project/myapp .
20docker push gcr.io/my-project/myapp