[sagher]

Further to Rudra's list of things, if you don't make your Domain Registration private, then your personal details including name, address and phone number gets listed on the Domain Registry WhoIs.  Everyone can get access to the registry and skim all your personal info from that list.  Next thing you get spammed, scammed, and a target for all kinds of things you don't want to happen to you. Better to get your Registrar to use his public address to cover your domain so if any legal person needs to get hold of you, they will do so through the Registrar of your Domain.

As an example you can check the Domain Registry below and see whether your domain is listed in it.  Then check the information it lists about you.  That is the information that every one else can get who uses the registry:
https://www.whois.net/

Purpose of this thread was to see where you can get this domain "privacy" for free.  Most domain registrars offer it these days, not all though.  Domain Silo has as a matter of its marketing principle that they offer domain privacy with all of their domains.

PS:  @rudra... that link to https://njal.la/ rocks!  Lovely Website too.  First time I've learned about it, many thanks for contributing it:

Is cloudflare also helps to hide personal information? any good free service to hide personal information?