The term Star of David was originally the Shield of David and was not first used in association with the six sided star. Later they became synonymous and the term cemented into the Star instead of Shield of David. Though in use in many different ways since that time, it did not become a general symbol of Judaism until the 17th century and only recognized internationally in the 19th century as symbolizing the Jewish people in both religiously and secularly.
That being said, some Orthodox Jews refuse to use the symbol because of its early use in magic. Spanish and Portuguese Jews tend not to use the symbol either.