article and section and div

• article — implies a "self-contained composition in a document".
• section — a generic section of a document
• div — has no special content meaning at all and is often used to provide containers or grouping for CSS

When to use each?

1. Self-contained content with a heading? - use article
2. Not self-contained content but without a heading? - use section
3. Otherwise, use div

MDN on article, section and div elements