WordPress is built with a library of modular blocks to allow users to build the page or post with the content elements that best suit their needs.
There are several custom blocks that were built as part of the Webspace Platform.
Widgets are a way to add content to your sidebar. You can add text, menus, images, HTML embeds and more. You can customize your widgets by navigating to Appearance > Widgets and adding and customising widgets in the Global Sidebar.