If no operator (+, -, * etc) is used you will get very general results. In other words, any word in this text string will give you possibly separate results:

abraham lincoln assassination conspiracy

You may get pages only dealing with Abraham of the Bible, pages dealing only with Lincoln Automobiles and pages dealing only with any assignations and conspiracies on record.

Put a plus sign before words that must be included in this query

abraham+lincoln+assassination+conspiracy

This will return any documents that contain all these words - BUT - you might find a conspiracy to assassinate Abraham Feldstien in his Lincoln Town car

Now we're getting somewhere - putting a line of text inside quotes is called a literal in code syntax. It must be rendered exactly as written

"abraham lincoln"+assassination+conspiracy

This will deliver pages that deal only with Abraham Lincoln's' assassination. You'll likely get pages with the history book version, separate ones with the conspiracy theory and ones with both.

"abraham lincoln"+"assassination conspiracy"

The above syntax will deliver only pages with the conspiracy theory.

Using a minus sign before a word will reject pages that contain that specific word.

"abraham lincoln"+assassination-conspiracy

This syntax will return results that only espouse the politically accepted version of the incident.

Just like in Poker the star, or asterisk is a wild card. Term must contain at least four characters or it will be ignored

car*

......................will be ignored

cart*

Will return pages with cartoon, cartography, shopping carts, oil and drug cartels, Cartegena Spain, ad infinitum. I honestly can't see much use for this, but there must be one.