Here are some of the most important ones: 

Phrase search: Usually, the moment you introduce more than one word into Google's search box, the search engine is smart enough to show you the most relevant results pertaining to that search. However, for those times when you need absolute accuracy, all you need to do is wrap your search phrase with double quotes ("your search phrase") and Google will present you with occurrences of the term you searched for, exactly how you searched for it. There is a risk though, that you might miss perfectly valid results by searching this way. Misspellings and middle names are common examples of this. 

Exclude terms: If you can customise your search queries to include only the exact term searched for, then most surely you can exclude terms from searches just as easily. To do so, all you need to do is add a minus sign (-) right before the word you want to exclude. For example, if you search for football -soccer, Google will exclude the terms soccer from its results. You can also use this parameter as many times as you want in one single search, just make sure to include a space before each and every minus when searching, otherwise it will not work. 

Fill on the blanks: This Google parameter could be considered the "wildcard" of searching. It is symbolised by an asterisk (*) and it will tell Google to use that space as a placeholder for unknown words and offer the best matches it came up with. For example, the term vegetarian soy *, will return results related to vegetarian soy recipes, vegetarian soy products, among others. You have to consider though, that this parameter can only be used for words and not for parts of words. 

One OR the other: Like in math and logic, Google uses the parameter OR (typed in upper case) to segregate the results depending on where the word is located. So, if you type bars OR cafes in California, Google will display results of either bars or cafes in California, depending on which it considers more relevant. By the way, the operator AND also exists, but it is the default used by Google in case you don't include OR, so there is no need for you to actually include it in your searches. 

Of course, as with any set of rules and parameters, Google also contemplates some exceptions to its rules. For example, words that are considered by Google to be "stop words", like "the","a" and "for" will be usually ignored unless it considers them relevant, like when searching for the music band The Cure. Punctuation signs, which are usually ignored, become an exception when it comes to some particular terms, like the + sign when searching for C++ (a programming language) and other similar ones. 

To sum up, even if most of the searches we conduct online are standard, there exist a set of values or parameters that can gives us a lot more control for those situations in which we need them. Besides, knowing these rules and exceptions can also help us avoid mistakes when naming or optimising our personal or business websites.