Lemmatization is the process of reducing a word to its base or root form, known as the “lemma.”

Unlike stemming, which simply cuts off word endings, lemmatization considers the context and morphological analysis of the words.

It ensures that the root word is a valid word in the language. For example, the words "running," "ran," and "runs" would all be lemmatized to "run."

This process helps in normalizing text data for natural language processing tasks by grouping together different forms of a word.