A search engine is a sophisticated software system that is designed to carry out web searches, which means to search the World Wide Web in a systematic way for particular information specified in a textual web search query. The search results are generally presented in a line of results, often referred to as search engine results pages (SERPs). The information may be a mix of links to web pages, images, videos, infographics, articles, research papers, and other types of files. Search engines utilize complex algorithms to index and rank content, and they crawl the web using bots, also known as spiders or crawlers, to find new content and add it to their indexes. In addition to the basic function of retrieving and ordering search results, many search engines feature additional tools and functions, such as spell correction, predictive text, and the ability to filter results by various criteria. The most widely recognized search engines include Google, Bing, Yahoo!, Baidu, and Yandex, each of which has its own unique algorithms and indexing techniques that affect how information is retrieved and presented to the user. The effectiveness of a search engine is determined by the relevance of the result set it gives back. While there may be millions of web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others, and those are the ones to which the search engine gives a higher ranking, thus making them more visible to the user. As the internet continues to expand, search engines and their algorithms are constantly evolving in order to better serve the needs of users.