Simplify the following text for a Grade 12 native English-speaking person.
Original: Strategic bombing is a methodology distinct from both tactical bombing and the use of strategic air assets in an operational capacity . Such a strategy usually involves sustained attacks over a period of time on targets that affect a nation 's overall war making capability , such as factories , railroads , oil refineries , and other resources .
Simplified: Strategic bombing missions usually attack targets such as factories , railroads , oil refineries and cities .