First however, let’s eliminate the confusion between the two ‘versions’ of WordPress …
The Difference between WordPress.org and WordPress.com
WordPress.org is the organization that develops and distributes the WordPress software. If you want to run WordPress on your own Web Host then this is where to get the software. WordPress.org also has a wealth of WordPress information and hosts most of the free Plugins (over 11,000) and Themes (over 1,200) available for download and implementation.
WordPress.com is a ‘freemium’ service that offers hosted WordPress software for free. There are various upgrades that, should they be required, cost a once-off or annual fee (an example of a paid upgrade is using your domain name on your WordPress.com site). WordPress.com hosts 11.5 million Blogs and these Blogs get over 2.5 billion Pages views per month
Here are the three core architecture elements of WordPress i.e. how it ‘fits together’.
Application and Database
WordPress connects to a Database that stores the data such as Page content and various settings. The use of the database makes WordPress a Content Management System (CMS). WordPress connects by default to the Open Source MySQL Database Management System (DBMS). MySQL is used by many of the leading companies and Websites (e.g. Linkedin, Youtube, Wikipedia and Walmart).
WordPress is capable of very many functions and is hugely extendible. WordPress software however ‘ships’ with the core most frequently used functionality. People are encouraged to make available extensions and these are called Plugins. Plugins are very simple to install into core WordPress and there are all sorts of capabilities available via the thousands of free Plugins e.g. ecommerce functionality, advanced SEO capabilities and form builders.
The ‘look and feel’ of WordPress is managed via Themes. A Theme defines the colours, fonts, layout and many other aesthetics. There are many free as well as paid-for and custom themes available and changing the Theme in WordPress is very simple. By separating the ‘look and feel’ of WordPress from the content and functionality, it becomes very easy to create using an entirely fresh looking Site without having to touch the content.
So above is the core architecture that makes WordPress the most popular used CMS. WordPress is suitable for all size organizations, free to extend, simple to use and very effective as a CMS!