A natural language processing (NLP) technique used by search engines to group together different variations of a keyword. Stemming allows search engines to understand that words with similar roots or stems have similar meanings, and to return search results that are relevant to the user's search intent, even if the search query doesn't exactly match the wording on a webpage.
For example, if a user searches for "running shoes", a search engine that uses stemming might also return results for "runners' shoes", "running footwear", and "jogging shoes", as these variations share the same root word.