Full-text databases such as Eighteenth Century Collections Online and America's Historical Newspapers are important resources for conducting research in historical fields. The ability to search for keywords and phrases across hundreds of thousands of pages is both an extraordinarily powerful way to identify relevant sources and a huge time saver for researchers.
However, the very power of full-text searching raises searching difficulties. Searching for slavery and indigo in Eighteenth Century Collections Online will result in a list of books that have both terms even if they are hundreds of pages apart. A search for slavery and indigo in America's Historical Newspapers will retrieve results in which "slavery" and "indigo" appear in different articles on the same page.
It is possible to ameliorate these and other problems by using proximity, phrase and wildcard operators that limit your search in rational ways that increase the relevance of your results. This guide lists the operators for some specific full-text databases.