How shall I understand the format of `/etc/resolv.conf`?

```
$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
search fios-router.home

```

Manpage of /etc/resolve.conf says

> 
> The different configuration options are:
> 
> 
> 
> ```
>    nameserver Name server IP address
> 
>           Internet address of a name server that the resolver should
>           query...
> 
> ```
> 
> 

So does `nameserver 127.0.0.53` mean that my local machine is running a DNS server whose IP address is 127.0.0.53? How can I find out its process? 

> 
> 
> ```
>    domain Local domain name.
> 
>           Most queries for names within this domain can use short names
>           relative to the local domain.  If set to '.', the root domain
>           is considered.  If no domain entry is present, the domain is
>           determined from the local hostname returned by gethostname(2);
>           the domain part is taken to be everything after the first '.'.
>           Finally, if the hostname does not contain a domain part, the
>           root domain is assumed.
> 
> ```
> 
> 

What does this part mean? The above just mentions what values that can be set to something, and does not explain what this part in /etc/resolv.conf means. Why does my /etc/resolv.conf not have this part?

> 
> 
> ```
>    search Search list for host-name lookup.
> 
>           The search list is normally determined from the local domain
>           name; by default, it contains only the local domain name.
> 
> ```
> 
> 

What does this part mean? What does `search fios-router.home` in my /etc/resolv.conf mean?

Thanks.