What does || mean in .screenrc?

Command based on Rampion’s command

screen /bin/sh -c '/usr/bin/man `cat "$@"` > /tmp/manual | less /tmp/manual || read'

|| read does not mean or in the command. read seems to be a built-in -command about which I did not find explanation in my OS X’s manuals.

What does || mean in the command?

What does || mean in .screenrc?