What is Courtesy ?
Courtesy is (noun) 1. politeness The hotel staff showed us every courtesy. She might have had the courtesy to apologise. Children should show some courtesy towards their grandparents. 2. (by) courtesy of as a gift from, with the kind permission of a box of chocolates by courtesy of the management He arrived home two hours late, courtesy of the train service.
source: Easier English, Student Dictionary Upper Intermediate Level