A SERP feature is any result on a Google Search Engine Results Page (SERP) that is not a traditional organic result (the old “10 blue links”).
The 15 main Google SERP features (as of January 2018) include:
Featured Snippets
Local Packs
News Packs
Image Packs
Tweet Boxes
People Also Ask
Instant Answers
Knowledge Panels
Videos
Sitelinks (in rich snippets)
Reviews (in rich snippets)
Thumbnails (in rich snippets)
Ads Top
Ads Bottom
Shopping