Simplify the following text for a Grade 9 native English-speaking person.
Original: A city designated by government ordinance , also known as a designated city or government ordinance city , is a Japanese city that has a population greater than 500,000 and has been designated as such by an order of the cabinet of Japan under Article 252 , Section 19 of the Local Autonomy Law .
Simplified: A city designated by government ordinance , also known as a designated city or government ordinance city , is a type of city in Japan . These cities all have a population over 500,000 people .