+ Use a plus sign before words that you want to appear in your search results with no variation of the word.
Google searches for all of your words, whether or not you put a “+” before them. I have seen people enter +search +words +like +this +into +Google, with a + before every keyword, but it is not necessary.
So when do you use the "+" operator? Use the "+" operator when you want the search word to appear in the results with no stemming; that is, no variation of the word. Google uses stemming technology so that it will search not only for your search terms, but also for words that are similar to some or all of those terms.
If you are searching for the surname Powers and do not want the words Power or Powered to appear in your search results, then search for +Powers. If you are searching for Kathi, and do not want results that for Kathy or Cathy or Cathi, then search for +Kathi. If you are searching for the surname Church and do not want results that contain the word Churches, search for +Church.
I usually do a search without the "+" operator to start but if I see that I am receiving results with unwanted stemmed words, I'll redo the search using the "+" operator.
Notice that there is no space between the + and the keyword. Be sure to try the Easy Google Genealogy Searcher which puts advanced Google features on one page with suggested keywords and advice about how each feature is useful for genealogy searches.