A domain name is simply just a collection of letters and sometimes numbers that have a .something at the end that let you find a internet resource(like email, website, etc.)
For the most part a domain name is not really all that impressive, but yet very important.
Even though a domain does not seem to do much, with out it we would have to type a IP address like 92.120.555.25 to pull up a website, or imagine sending an email to your co worker to this email address: firstname.lastname@example.org yikes!
So needless to say they are deceptively important. They don’t make a website, they don’t make a email address, they just make it a lot easier to locate those things. Without them, life would be… a bit more technical.