Ever wanted to change or test a new WordPress theme without making the new theme public yet? Changing WordPress themes should be as easy as clicking a template on the Appearance/Theme page of your WordPress dashboard. However, some advanced WordPress users like to tweak the template/CSS to suit their preference. It’s hard to tweak the template before changing a theme because you’re not sure whether the tweak will look right or not. Often times, you have to change the theme first, then tweak the template one modification at a time. You have to refresh your website to see each change until you are satisfied. Meanwhile, all your visitors are seeing all the changes you are making at the same time and it’s likely that your website will exhibit strange and odd behaviors.
I found a WordPress plugin called Theme Tester that you can use to test new WordPress themes without letting your visitors see any changes. As long as you are logged in to your blog, you will see the new theme and all the changes, but no one else will until you disable this plugin. Very useful!