WordPress is an open-source content management system designed to allow businesses of any size to build and publish websites. Because it is open-source there are endless options for themes, modules, and extensions to build your website.
With a never-ending amount of custom themes, plugins, extensions, and options, WordPress is set up to allow you to build the website you're dreaming of.
Because WordPress is the world's largest content management system, naturally a lot of communities and support forums have been developed. There are also many marketplaces and resources to find, purchase, and download resources for your WordPress website.
One of the biggest perks of WordPress is that the software is free (though some plugins, themes, and extensions will have costs). You can get started with WordPress and even build on any of their free themes for absolutely no cost.
Since WordPress is open-source there have been many eCommerce options developed to accomplish any online store's goals. Plus, with most eCommerce plugins you can setup nearly any payment processor that you prefer.