A WordPress blog is easily customized with themes. A theme affects more than the appearance or style of the blog; it also defines what information is displayed and where. In fact, once you choose a theme, you can change its appearance by editing its CSS files or using a child theme.

I chose the K2 theme for Impolite Company and blogan.net for the following reasons:

• K2 Sidebar Manager. WordPress supports widgets that display recent comments, calendars, blogrolls, etc., on your blog’s sidebar without programming or editing your theme’s files. Unfortunately, WordPress’ widget support displays the same widgets on every page of your blog.

  K2 Sidebar Manager lets you control where on your blog each widget appears: the main page, individual pages, single post pages, the archives page, or even individual posts. I use K2 Sidebar Manager’s display feature to restrict my lengthy blogrolls and Google Reader shared items to the long main page.

  Note: WordPress is planning to add most of K2 Sidebar Manager’s functionality. Once that happens, all themes will be able to take advantage limiting where widgets appear.

• Configurable columns. K2 can have zero to two sidebars in addition to the main content column. The width of the header and page automatically adjusts and K2 Sidebar Manager automatically supports placing widgets in these sidebars. If you want, the blog can be screen width aware and move the sidebars to the bottom of the page if a visitor’s screen width is too narrow to display the sidebars beside the main content.
• Archives page. K2 creates an archives page that allows visitors to browse your posts by tag, category, or date. Nice!
• Page menu. When you create a WordPress page, K2 places its title in a horizontal menu in the bottom of the header. This is handy for “About” and the archives pages.
• Custom CSS file. K2 supports a custom CSS file that changes the appearance of your theme and can be selected from your K2 Options screen. It operates like the child themes mentioned above. Keeping your custom CSS separate from the core K2 files simplifies the upgrade process when a new K2 version becomes available. The custom CSS file also defines the size of your header, enabling WordPress’ header upload function to crop to the correct proportions for your blog.

  My custom CSS file changes my colors, background images, fonts, link styles, and supports some plugins. I also use it to unclutter my blog by hiding some extraneous icons and messages I don’t want to display.

  K2 comes with two sample custom CSS files to get you started.

K2 has some other features that I’m not currently using, but you might find useful.

• Asides. K2 allows you to designate a category as an “aside.” K2 will display all posts in this category with different styling. If you choose inline asides, the post title uses a smaller font. For sidebar asides (which uses K2 Sidebar Manager), the an aside’s title doesn’t display, just its text.

  Asides are useful for short posts. For now, I use Twitter as a “microblog” and import the “tweets” into my sidebar using Twitter Tools. Josh Bancroft uses Twitter Tools to save his tweets as asides in his WordPress database and have them displayed in a sidebar.

• Advanced navigation. K2’s advanced navigation is an AJAX capability that can load older posts without having to reload the entire page. I go back and forth as to whether I like it. I’m not using it right now.
• AJAX commenting. When someone leaves a new comment, AJAX commenting displays it at the bottom of the list of comments without reloading the entire page.
• Live search. Live search displays search results as someone start entering letters in the search box.

What theme did you choose and why?

Next up, content plugins.

Update 10/1/08. The latest K2 nightly build now supports threaded comments, but no longer supports AJAX commenting.