To strive is to try very hard, over a long time, to reach something difficult — and the word carries the effort in it. You do not strive to open a jar; you strive for peace, for excellence, to be a better person, to finish a degree while working nights. Two things make it different from ordinary try. First, the goal is usually big, worthy and far away, often something you may never fully reach. Second, the word is formal and rather noble-sounding; it belongs to speeches, mission statements, school mottos and serious writing more than to daily chat. If a friend asks what you did today, you would say "I tried", not "I strove". It is followed by for a thing (strive for accuracy), by to and a verb (strive to improve), or by after a goal in older or more literary writing. There is an old, mostly dead meaning of fighting or quarrelling with someone — that survives in strife, which still means bitter conflict. Though actually, because companies overuse it in advertising ("we strive to deliver the best service"), it can now sound a little empty if you are not careful; use it where the effort is real.