Proximity search is a form of advanced search where the assumption is made that the proximity of words implies a relationship.  All major search engines like Google, Bing, Yahoo etc. use proximity search to improve the relevance of matched pages returned for a search.

Keyword proximity is how close words are to each other in most parts of the website (i.e. , the meta tags, headlines, page title, descriptions, page headings and page content). Keyword proximity is an important factor that influences how search engines find the content on the site.

Stop words are mostly ignored in the keyword proximity assessment. As pages must be designed for people and not for search engines, these stop words should not be excluded when composing the page. However, the stop words are not needed in the meta keywords.