What is mean the setup unix:///var/run/docker.sock/?

Hi dears,
I saw in many pipelines the unix:///var/run/docker.sock, but not understood what is the flag unix:/// in this context?
What is unix:///, what is used for?

Its an URI that points to a unix domain socket - in this case the docker.sock. The docker engine creates the unix domain socket when started and is used as a local endpoint to control the local docker engine that created it.