Extended definition
The Google results page when you search for something. Contains organic results, ads, AI Overviews, featured snippets, knowledge panels.
Context and application
Modern SERP is a collage of elements: ads (top), AI Overview (when present), featured snippet (position 0), knowledge panel (lateral, for known entities), organic results (10-20), People Also Ask, Related Searches. Different queries produce different layouts. For your SEO analysis, what matters isn’t just organic position, but how much “visual space” you occupy on SERP — a rich snippet on position 5 can produce more CTR than a plain result on position 2. Tools like Ahrefs and SEMrush have a “SERP features” report showing what features appear on your queries.