WordPress as a platform and as a community of users has grown in two main areas. The first one is gathered around WordPress.org (https://wordpress.org/), the native, main website of the WordPress project. The other is WordPress.com (https://wordpress.com/), a platform providing free blogs for every user who wants one:
Essentially, WordPress.org is about developing the platform itself, sharing new plugins, discussing the technical aspects of WordPress, and being all techie in general. WordPress.com (the preceding screenshot) is a purely community-driven site where bloggers can meet with each other, and publish their content on free blogs under the wordpress.com subdomain (for example, something like https://paleorecipeslog.wordpress.com/ is a subdomain). That being said, there are paid plans available at WordPress.com as well.
In Chapter 2, Getting Started with WordPress, we will discuss all of the differences between having your blog on WordPress.com and 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, which obviously has its pros and cons.