WordPress is both an online Blogging site where you can set up your own free blog and software you can download and install on your own website. The online package is generally just for blogging. The site you install yourself is a full-featured content management system (CMS) website.
At the online site you can probably get your own blog started in less time than it takes you to read this sentence. All you need is an email address and a name. You can blog as much as you want for free, your blog can be public to the world or private for just your friends, and the paid upgrades are completely optional. If you are uncomfortable working with software on your own computer or your web host then the online blog is the likely way for you.
WordPress blogging software is an easy installation. Some hosting sites will install it for you or offer an easy install process. If not you will need to know how to unzip a ".zip" archive file and how to transfer the resulting folders and files by FTP to your web host.
Your web host will need to support specific versions of PHP and MySQL. You will need to set up a MySQL database and know the database name, login and password.
The actual installation process is lightning fast. Setup takes only a few minutes and the learning curve for the whole system is quite low. If you are at all technically inclined this may be the route to go for any type of website from a basic blog to a full-blown ecommerce shopping cart site.