What is a 'fourth-level domain'?

What is a 'fourth-level domain'?

After the domain name, there can be other initials and symbols such as '.uk' or '.st' and that is just signifying further in the email address where something is. So in other words, if you are going to email into a specific address, in the UK they might have yahoo.com.uk.something else, and that is just further specifying the exact email address or internet protocol, the ip address for that particular email address. So in other words, the more you have, the more specificity to that level because there are lots of people in UK with email address and you need a greater and longer email address, just like the telephone numbers are.