Keyword stemming refers to the procedure undergone by search engines as well as natural language processing for reducing words to their root, or stem. “Running,” “runs,” and “ran” would all be considered stemming for “run.” This has a positive effect on search relevance by allowing for the possibility of matching user queries with web pages that contain variations of a keyword, not necessarily appearing in its exact form. In effect, stemming equips search engines with the capability of understanding the very meaning of the word, quite irrespective of its form or tense. Stemming thus constitutes an additional and highly useful functionality for search; however, in certain instances, it might create problems of overgeneralisation and imprecise matching. Most of the modern search engines go for a far higher degree of sophistication, such as lemmatisation, which accounts for the context of the word and gives back a corresponding valid dictionary form (lemma) instead of a mere stem.