Search engine is a.
Search engine is a Software.
A web search engine is a software system that is designed to search for information on the World Wide Web. 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 web pages, images and other types of files.
A search engine is a web-based tool that enables users to locate information on the World Wide Web. Popular examples of search engines are Google, Yahoo!, and MSN Search. ... The information gathered by the spiders is used to create a searchable index of the Web.
"Better" is a tough thing to define because it's based in opinion, but there are plenty of options. I think Google is still the superior engine, but Bing (which also powers Yahoo) is a formidable search engine.