A category of information that Oracle Expert collects and analyzes. The collection classes are Database, Instance, Schema, Environment, and Workload.
In object-oriented programming, a collection class is any class that is capable of storing other objects. Collection classes usually implement some kind of data structure, such as a list, map, set, array, or tree. A collection class is usually able to store an arbitrary number of data items, i.e. the size of the collection is adjusted automatically.