Every website needs a website address e.g. www.perthwebsitedesign.com. This is otherwise known as a domain name. It is a good idea to secure a domain name before even having your website built, in case someone else purchases it first.
 

The importance of a domain name comes down to search engine results, if you intend to generate business through search engines. Because search engines return results based on keyword entry, your domain name should contain words that are either the same as the name of your business, or relative to the goods and services you offer.
 

A good domain name is one that reflects the name or nature of your business. I.e. If your business is called Monster Music, a well suited domain name would be www.monstermusic.com.au.
 

Lets say Monster Music offers music tuition in Perth. It is very likely that someone would enter "music tuition perth" into a search engine if that was the service they were hoping to retrieve results for. Therefore, being that those are likely keywords for that type of business, Monster Music would also be very wise to register a domain name such as www.musictuitionperth.com, in hope of a higher position in search result pages.