How is Content Builder organised, and what types of content blocks are available?

Content Builder uses a folder hierarchy for organisation (similar to a file system). Tags provide a cross-folder labelling system for quick filtering. Shared content lives in a parent Business Unit and is accessible to child BUs. Global content is locked content shared across BUs that child BUs cannot edit.
Content block types:
— HTML block: Raw HTML for complete custom control.
— Text block: Plain text or rich-text editor content.
— Image block: Hosted or external image with alt text and link.
— Button block: Styled CTA button with configurable colours and URL.
— Dynamic content block: Rule-based or AMPscript-powered content variation block.
— A/B test block: Two or more content variants for split testing within a single email slot.