No doubt that wordpress is very popular blogging platform now. One of the best features from WordPress is you can use a lot of different wordpress themes available on internet. Some free and some commercial. For getting free wordpress themes, WordPress has its own official themes repository. All of these themes are free. But you can also get some themes from other site.
Every WordPress theme is unique and can be characterized based on
You can use 3-layout, 2-layout or even 1-layout theme depends on what information you like to put in. For 2-layout, you can choose left sidebar or right sidebar.
Some themes come with dominant color. It could be dominated by green, yellow, brown, blue or two colors combination and three colors combination.
Almost wordpress themes today support widget feature. It means that you can many widget into your used wordpress theme. The location of widget is differ depends on theme. Some theme can allow you to put widget on bottom area or top area.
Not many wordpress themes support this feature. With internationalization feature, you can switch the current language (English) into your language (if it is supported).
5. Custom Header and Custom Background
WordPress 3.0 started to allow user to change the header and the background of theme they are using. So, themes become more flexible to be changed on your own. These two features become what-a-must-have option to be created for theme developers.
6. Other feature
Like Cufon font or custom font, theme options (you can configure extra options for the theme), color scheme (switch to different color) are example for other wordpress feature.
Not all free themes are bad. Some of free themes also as good as the commercial ones. So, pick the best free one is better for you. Even, several WordPress web hosts also give you a special theme.