Google, Bing, Yahoo are all search engines, but what is a search engine anyway? A search engine crawls the Internet and ranks content. When you tell a search engine you want to find "red toys," for example, it returns a list of websites which contain both "red" and "toys."
This list would not be much help, however, if search engines did not filter the results and order them by relevance. We don't really want just any website with the word "red" in it. We only want it if "red" is prominent. We don't want websites who mention "toys" once. We only want it if "toys" appear many times. Even better, we want websites which mention "red toys" as a phrase. If the domain has "red" or "toys" in it we are more interested. If page titles mention "red toys" we likely want to see that page. If headings list "red toys" that should be at the top of our list too!
Search engines score your web pages and the site as a whole for its score and rank pages by that score. The list of criteria and algorithm they use is complex and secret. But many rules can be figured out. Here is a simple list of things which give your web page a higher score
There are many other factors. Among them:
Understanding how search engines rank your website will help you understand what you need to do in order to rank highly.