What is meaning of .org, .in , .net ,.np , com?

These are domain names.A domain name is an identification label that defines a realm of have below:-
.np-nepal
.org-organisation
.in-india
.net-network
.co.in-company in India
.uk-united kingdom
.com-commercial organisation
.pk-pakistan
.au-australia
.edu-educational institutions
.ac-academic institutions
.res-research institutes
.ernet-educational and research institutes
.gov-government site
.mil-military


and the list is endless..........