Search engines like Google Scholar use something called natural language searching -- which means that you can just enter an entire sentence in the search box and run a successful search. The search engine will choose what it thinks are the most important words and search with those. Library databases, however, don't accept natural language.
Suppose you're looking for information about the possible impact of video game violence on teenagers.
A search with a simple natural language sentence returns about 41,000 results in Google Scholar:
But the same search in the library database Web of Science doesn't return any results:
Evidently, the search syntax -- the structure of the search query -- is invalid (not correct) for this database. But how to tell a database exactly what you want it to do in its own 'language'? That's what Module C is all about.