Keyword proximity measures how close two or more keywords sit to each other within a passage of text. In a multi-word search, the nearer those words appear together on your page, the stronger a match search engines tend to judge that passage — tight phrasing reads as more relevant than words scattered across a paragraph.
Suppose someone searches for "waterproof hiking boots." Two product pages both contain all three words:
Page A keeps the exact phrase intact, so its proximity for that query is high. Page B splits the terms across two sentences, weakening the signal even though every keyword is present. All else being equal, Page A has the edge.
Semantic search has softened proximity's influence — Google no longer needs words glued together to grasp intent, and it treats close relatives of keyword density with the same nuance. But the signal still surfaces in high-value spots: page titles, H1s, product names, and link text, where a clean, intact phrase communicates relevance instantly. It also shapes how featured snippets get pulled, since concise passages containing the full query are easier to lift.
Rather than engineering proximity, write specific headings and product titles that naturally hold the phrase together. That habit tends to satisfy both proximity and readability, which is the balance on-page optimization is after.