This will filter your search returning only what passes through the filter. Of all the sites containing the word cars you will only see those that contain the word ford. This command searches for a specific title. Fuzzy search capability. Choose this whenever you can.
Fuzzy technology makes sense out of, well, fuzzy input.
A search engine is software that queries a database. No single search engine scours the entire Web for information. Not yet anyway. Your search will be submitted against one, or more in the case of multi-threaded search engines, databases. That's why it is important to use various search engines if one or more does not find what you want.