Does Docker create a default network, or does it need to be created manually?

In Docker, three default networks are created during installation:

1. bridge: The default network to which new containers are connected unless specified otherwise. Containers in this network can communicate with each other via IP address but are not accessible from outside without port forwarding.
2. host: The container uses the host's network stack. There is no network isolation between the container and the host.
3. none: The container is not connected to any network.

Custom networks can be created additionally using the docker network create command.