Whilst Google is considered the biggest, or at least most popular search engine, there are thousands of other search engines available. Some of these are direct competitors, offering a comparable but different experience, such as Bing, DuckDuckGo, Yahoo, Ask and more. However, there are many more smaller search engines, including a huge number of smaller ones that search a specific website, document type or social media outputs (e.g. YouTube, Instagram). New search engines appear all the time, just as existing search engines can disappear, or rapidly change functionality.
No search engine indexes more than a small percentage of the visible web. As such it is advisable not to depend on a single search engine, particularly when conducting literature reviews. Each engine will index a different range of pages. They might overlap in coverage a great deal but will also differ in what algorithms they use to retrieve and rank results. Some search engines like Google will learn from your past searches and increasingly personalise results.
In addition, most of the web is ‘hidden’; content that cannot be indexed by search engines, largely because it is either password protected or behind a paywall. This includes a lot of the content within the expensive 100+ electronic databases the Library subscribes to for finding scholarly literature, data and other content for learning and teaching. You may find Google Scholar and some subject-specific search engines (for example TechXtra https://www.researchinformation.info/product/techxtra) are complimentary when conducting literature searches and may index papers that you can also find in the scholarly databases, but they will not find or provide full-text to everything.
If unsure where to start or which alternative search engines might help you diversify your web searching approach, you could try a meta-search engine. These apply your search across multiple search engines at once then collate results from these. This can give you a quick sense of the differences in results and perhaps highlight other search engines with particularly relevant results you would like to try. Popular meta search engines include for example DuckDuckGo, MetaCrawler, Startpage, Draze and others. There is also social-searcher.com specifically for searching social media content
As search engine functionality evolves and new content formats come and go, it is very useful to think about which are going to work best for your search, strategies for composing effective searches and then refining your results.
Links to other search engines