Fact Sets: A fact set is a single directory containing multiple facts, where a fact defines:
* The entity the feature value is associated with;
* An attribute specifying which feature;
* The value itself;
* The time from which the feature value is valid.

Feature store: A feature store is comprised of one or more fact sets, which is represented by a text file containing an ordered list of references to fact sets.

Dictionary: All features are identified by their name and namespace. In the example fact above, the feature is widgets:inbound.count.1W where widgets is the namespace and inbound.count.1W is the name. With Ivory we must also associate with any namespace-name feature identifier the metadata.

Queries: Ivory supports two types of queries: snapshots and chords.

Data Generation: Ivory supports generating random dictionaries and fact sets which can be used for testing.