Which HTML element is primarily associated with defining a block in Shopify theme development?

The section element is primarily associated with defining a block in Shopify theme development due to its role in organizing content semantically. In the context of Shopify, sections are used to create reusable and customizable components within a theme. This organization allows for better management of the layout and structure of web pages, enabling developers and store owners to create dynamic content layouts.

The section element can contain various types of content, including headings, paragraphs, images, and other HTML elements, making it versatile. Additionally, sections are recognized by the Shopify platform as components that can be easily added, removed, or rearranged in the theme editor, facilitating a more user-friendly experience when updating the online store.

While the div element is a common block-level element used in HTML for grouping content, it lacks the semantic meaning associated with sections in the context of Shopify. Blocks and templates refer to specific concepts in Shopify's Liquid templating language rather than representing the HTML structure used to build content layout. Thus, the section element stands out as the appropriate choice for defining blocks in Shopify theme development.