Entity–attribute–value model (EAV) is a data model to encode,
in a space-efficient manner, entities where the number of attributes (properties, parameters) that can be used to describe them is potentially vast,
but the number that will actually apply to a given entity is relatively modest.
Such entities correspond to the mathematical notion of a sparse matrix.
EAV is also known as object–attribute–value model, vertical database model and open schema.