What is the role of stemming and lemmatization in indexing services?

Stemming and lemmatization are text normalization techniques used to improve search relevance. Stemming reduces words to their root form (e.g., 'running' -> 'run'), while lemmatization finds the dictionary form of a word (e.g., 'better' -> 'good'). By applying these techniques, indexing services can match variations of a word, increasing the chances of finding relevant results.