WordPress allows publishers to use various themes that are available along with the tool or even custom made to suit your aesthetics. There are hundreds of websites that offer a variety of free WordPress themes that can be downloaded and used to create beautiful pages for your blogs or ezines. High quality themes are not always free for most applications. But WordPress being an open source platform, there are many designers who cater to the needs of the community without charging a single penny. Some of the themes are customizable, which means if you have the knowhow you can play around with the code and modify them without having to start from scratch.
Before the use of themes became a popular phenomenon for any web based tool, WordPress functioned using a single page with files to support display of comments and article submissions. There was only a single sheet which controlled the presentation. Other pages were generated using different parameters that were fed into the original page. The advent of free WordPress themes changed all that and now the user can directly download structured themes that suit WordPress for free.
A free WordPress theme is fundamentally nothing but a skin for your webpage but at the same time is also something more. Apart from the different designs, these themes can provide different ways of controlling the appearance or presentation of your website. A theme usually consists of a collection of files put together to generate a uniformly designed user interface for weblogs. Modification of a theme does not in any way change the underlying software. It merely changes the style of design or presentation of the page. These free themes are so customizable that it is a common practice among bloggers to use a unique theme for each post that they put up. The themes can also be made to resonate on the same wavelength as the content. For example you could use a general car based theme for an article or a submission that talks about cars in particular.
The first set of free WordPress themes that were available were put into an official directory hosted by WordPress itself. These themes were reliable in that they were checked and verified for spam or malicious code and then made available for downloading. The directory still is quite active with more people preferring to download verified themes from rather than going for sponsored themes available for free elsewhere. The directory allows search features based on type and style and also allows the downloader to have a preview of the theme to get a better idea as to how it looks.
The free WordPress themes can be managed using an admin panel that is made available to you. You can add whichever themes you like to your directory and they appear on your panel. There is also the option of uploading themes to a particular directory on the server using the control panel provided by your host. Selection of themes can also be done using the administration panel. WordPress also lets you create themes from scratch if you want to. There are tutorials that teach you how to build and distribute themes.