How to manage millennials and retain them in your team

Millennials are people born in the 1980s and 1990s, so they are now roughly 24-43 years old. They form a large part of the workforce and, compared to older (and also younger) generations, they have certain specific characteristics which, among other things, require they be treated differently from a managerial perspective. So how should a team leader manage millennials to ensure they are productive and happy, and to retain them at the company and in their team?