Ranking
A ranking is the position a page holds in the search results for a given keyword. If your page sits as the third organic result for "running shoes for women", your ranking is 3 on that keyword. Taken together, a site's rankings describe how visible it is in search.
A ranking is not one fixed truth. Results shift with the user's location, language, device and search history, and Google adjusts its algorithm continuously, so two people rarely see the same order. Rankings are therefore read as averages over time: Google Search Console reports average position per query, and rank trackers follow the movement day by day across a prioritized keyword set.
Clicks gather at the top of the SERP, and the distance between page two and the top three shows up directly in traffic. Movement in rankings is also one of the earliest signs that SEO work is landing, since it appears here before it appears in revenue.
AI search has no numbered list in the same sense. A ranking there becomes whether the answer mentions or cites you, and what share of the answers in your category you turn up in. A full picture of a position in search now holds both sides, and measuring it is the subject of the guide to visibility tracking.