Maybe you are wanting to learn WordPress or experiment with WordPress but do not yet have a hosting service. Or maybe you have an existing WordPress site and want to have a way to try new themes or layouts without risking crashing your site.
A localhost is way of putting a complete WordPress install in your computer. You can do almost everything on a local host install that you can do on a regular hosted website install. You can also download your current WordPress site to your local computer and run it as a local host, make changes, try different things and not effect you current site.
WordPress installs on a local host can be uploaded to your current site or hosting. Desktop Server has a good easy to use local host that works on both PCs and MACs and gives you the ability to have a complete working WordPress install on your computer. Even if you do not have a web site or hosting yet here is a way to learn WordPress, design and test what you would like your web site to look like and how you want it to work. Most themes and plugins will work with a localhost install.
Desktop Server has a free version which will work just fine for many people – there is also a premium version with some added features that you might find useful. Start with the free version, use it to learn WordPress, to experiment with themes and plugins and as a place to learn the more advanced applications like CSS for fine tuning and treaking sites.