Definition
Structured snippets are the enhanced SERP elements engines render when they detect structured data: sitelinks (additional pages under main result), star ratings, prices, breadcrumbs, FAQ accordions, video thumbnails. AI engines use the same structured data to enhance their generated answers: Product schema with priceRange surfaces in AI Overview comparison answers, FAQ schema fills 'people also ask' tiles.
A product page with Product + AggregateRating + Offer schema gets rendered in AI Overview as a comparison card with star rating + price.
How to optimize
Add the right schema type for each page intent. Test in Google's Rich Results Test before deploy. Track which Rich Result enhancements appear in Search Console.