There are many types of domains having different types of extensions.
1) .net = It is mainly used internet service provider.
2) .org = It is used mainly by non commercial organization.
3) .biz = It is mainly used for business purposes.
4) .info = It is mainly used for site that are mainly designed for provide any helpful resource. whether it is commercial or non-commercial.
5) .co.uk = It is mainly used for businesses.
6) .org.uk = It is mainly used for non-commercial organization.
7) .me.uk = This extension is mainly used for personal use.
8) .com = It is used for general purposes.