To explain this question better, let’s use an everyday example. When you want to build a house, first you buy the land at a specific physical address. Then you acquire building material and start building your house following your desired plan from your architect. Lastly, you acquire a mail box so that the postmen can easily put your letters in it.
The house that you build with the acquired building material is the website that you design with text, pictures, videos, etc. The plan that you use to build the house is the theme for your website. The physical address for your house in the case of your website is the unique URL for your website also known as the domain name for example makuruwan.com.
Now website URLs are linked to unique IP addresses (which are a series of numbers for example 19.121.137.08) such that each time you want to visit Makuruwan.com you can just search for 19.121.137.08 on Google and it will identify our website on the internet based on the IP address.
However, it is difficult for humans to remember strings of numbers like the one I have just used. Because of this, domain names were developed and used to identify websites on the Internet rather than using IP addresses for example youtube.com, makuruwan.com, facebook.com, and it can then be used in combination with various domain name extensions, such as .com, .co.uk and many more.
Just like the case where there can’t be the same physical address for different pieces of land, there also can’t be the same domain name for two separate website owners. If you try to register a domain that is already registered by someone else, for example makuruwan.com under your name, you will fail to do so because Makuruwan Web Services already own it.
Just like the case where there can’t be the same physical address for different pieces of lands, there also can’t be the same domain name for two separate websites. The land that you build your house on is the web hosting for your website. This is where your website files are going to live and lastly the mailbox for your home is your professional email address.
To summarize, a website is a collection of web pages that are usually related in terms of the type of content that it publishes, identified by a unique domain name and hosted on at least one web hosting service provider.