How to expose container's ports?

How to expose container's ports?

Options Used for port expose: 

--publish, -p Publish a container’s port(s) to the host
--publish-all, -P Publish all exposed ports to random ports

Commands:

[root@localhost ~]# docker run --name 'nginx2' -P -itd nginx
[root@localhost ~]# docker run --name 'nginx3' -p 1521:80 -itd nginx