One very useful characteristic of WordPress is that it has a large, active online community. Everything you will ever need for your WordPress website can be found online, and probably for free.
As WordPress is always actively developed, it's important to keep yourself up-to-date with the software community about their latest activities. The most important spot to visit or subscribe to is WordPress Releases: http://wordpress.org/development/category/releases/. Whenever there is a new release—be it a major release, or an interim bug fix, or an upgrade—it will be here.
Also, be sure to stay tuned to the main WordPress blog at http://wordpress.org/development/.
The WordPress Codex is the central repository of all the information the official WordPress team has published to help people work with WordPress.
The Codex has some basic tutorials for getting started with WordPress such as a detailed step-by-step discussion of installation, lists of every template tag and hook, and a lot more. Throughout this book, I'll be providing links to specific pages within the Codex, which will provide more or advanced information on the topics in this book.
There are official directories for themes and for plugins on wordpress.org. Though not every theme and plugin is available here, the ones that are here have been vetted by the community to some extent. Anything you download from these directories is likely to be relatively bug-free. You can also see what the community thinks of these downloads by looking at ratings, comments, and popularity.
Additionally, plugins in the Plugin Directory are automatically upgradable from within your WordPress Administration Panel, whereas other plugins have to be upgraded manually.
Theme Directory: http://wordpress.org/extend/themes/
Plugin Directory: http://wordpress.org/extend/plugins/
You'll notice that all of the URLs above belong to wordpress.org. There is another website, wordpress.com, which is actually a free blog-hosting service. Anyone can open an account on WordPress.com and instantly have his or her own WordPress-driven blog. According to WordPress.com, there were over 6 million blogs on WordPress.com and over 9 million active installations of the WordPress.org software as of December 2008.
In Chapter 2, we will discuss all of the differences between having your blog on WordPress.com versus downloading the software from wordpress.org and hosting it yourself, but the basic difference is the level of control. If your blog is on WordPress.com, you have less control over plugins, themes, and other details of the blog because everything is managed and made worry-free by the WordPress.com service.