Compare a bounded type parameter <T extends Number> with a wildcard <? extends Number>. When do you need each?

Use a named type parameter <T extends Number> when you need to refer to the type elsewhere in the signature — relating arguments to each other or to the return type (e.g., <T extends Comparable<T>> T max(List<T>)).

Use a wildcard when the method doesn't need to name the type and just operates on 'some unknown subtype', which keeps the signature simpler. A rule of thumb: if a type variable appears only once and you don't need its name, a wildcard is the cleaner choice.