The first part tells you what protocol to use, in simple terms it is the method you want to use in order to reach the resource you want http:// being via HyperText Transfer Protocol. Most addresses you find online are http URL addresses however there are others such as ftp:// which is for getting files via the File Transfer Protocol.
After the protocol comes the domain name which points you in the direction of the web server at which the resource is held. In the example above the domain name is getdotted.com, this then gets converted into an computer understood address known as an IP address of where the resources are held. If you do not already own a domain name then you might want to consider registering one in order to point towards your web hosting or use with a Freeola500 free URL. Find out more about domain names.
The last part is the all important resource location. This is where the file can be found on the web server, the example above is referencing the file domain-name-types.php within the root directory /.
If a file was held within a folder below the root directory then the resource location would include a bit more for instance Freeola Support pages are all held within the support folder, for guides on domain names /support/domains.php.
That is not the only reason why you should care about URLs however, your visitors count too! A URL should be easy to remember at best and easy to read out at it's worst. So for a blog article the following would be a lot better for users:
The former will do a lot to simplify reading it out, understanding what the page is about and sharing the link which is important to most, if not all web masters.
There are other more simple solutions too, for example structuring your website in an organised fashion with folders for various sections of your site with useful names goes a long way for making your URL's more comprehensible. For example say you maintain a football club website, you might want to structure your website something like this: