What are commonly used words that do not add meaning to the primary search terms referred to as?

The terms that are commonly used but do not add meaningful content to primary search terms are known as stop words. Stop words typically include words such as "and," "the," "is," "in," and "at," which are often filtered out by search engines during the indexing process because they do not contribute significant meaning to search queries. By eliminating stop words, search engines can focus on the more meaningful keywords that enhance the relevance of search results.

Other terms in the choices can be distinguished as follows: keywords are the significant words or phrases that represent the content of a search, filters help refine search results based on specific criteria, and modifiers are words that alter or clarify the meaning of a keyword. These distinctions help clarify why "stop words" is the correct answer, focusing on the unnecessary words that do not impact the essence of a search term.