What are Subdomains?
If you have a domain name, say www.mybusiness.com, then you can have subdomains like www.furniture.mybusiness.com, www.hardware.mybusiness.com etc. Subdomains do not require registration - they are free. They just need to be setup on your hosting to point to the folders of information that you want them to display.
You can achieve the same result by having folders under your domain name like
Our Linux host does allow the format www.furniture.mybusiness.com
although some hosts don't.
This can be overcome by registering domain names for each sub-domain, e.g. myfurniture.com and myhardware.com, and parking these on the hosting plan for mybusiness.com. These can then be redirected to the folder for each sub-domain. e.g. www.myfurniture.com opens the folder allocated to furniture.mybusiness.com. Then you have several websites but pay for only one hosting plan.
Of course you should choose the name of the main website carefully. It would not look businesslike to a visitor if the address bar showed http://myfurniture.mypersonallife.com
Do it through Platypus Hosting and get the style www.furniture.mybusiness.com.au