Data is a value that can be fully represented by bits. It can be serialized for persistent storage or transfer over the network. The fields of the data object must also be data. Most entities in a typical program--such as integers and strings--are data.

The library provides a lot of functionality for subtypes of data, such as equivalence predicates, hash functions, and serializers.

Examples of values that are not data are a clock or a file descriptor--since they refer to entities that cannot be packaged and sent over the network.