While entity detection may seem to be a simple task, there's actually some significant processing going on. Try using the sentence "The Eiffel Tower is one of many highlights in Paris, France." and examine the entities it extracts. These should include "Paris" and "France." While this may seem obvious, change the sentence to "The Eiffel Tower is one of many highlights in Paris, Texas." The API no longer finds the entity "Paris" (the city in France). Instead, it just finds the city "Paris, Texas."