Each website in the world is identified by a unique number (IP address), just like international phone numbers, for example 18.104.22.168.
As these numbers are hard to remember, unique words and phrases are used to permanently link to these numbers. So instead of typing the long number above, it's much easier to remember and type lifewire.com, which will redirect your browser to the the IP address above, where the actual website is hosted. The domain extensions show the country of registration of that domain. For example .eu is European Union, .me is Montenegro etc.
Web hosting is a service that allows organizations and individuals to post a website or web page onto the Internet. A web host, or web hosting service provider, is a business that provides the technologies and services needed for the website or webpage to be viewed in the Internet. Websites are hosted, or stored, on special computers called servers. When Internet users want to view your website, all they need to do is type your website address or domain into their browser. Their computer will then connect to your server and your web pages will be delivered to them through the browser. (Cited from website.com)