سوال ۱۸ کنکور ارشد مهندسی کامپیوتر ۱۴۰۱

PASSAGE 1 (relevant excerpt):

When a user enters a query into a search engine (typically by typing keywords), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document title and sometimes parts of the text. ... Also, search engine ranking methods change over time as the way users interact with internet services changes and new techniques evolve.

Question: The word "evolve" in the last line of paragraph 1 means ----------.