On the planet Betazed, a House was a name that was given to the eldest and most influential families in Betazoid society, who could trace their ancestry back to the earliest writings in Betazoid history. There were twenty Houses, and a numeric designation was given to each house based on how far back their ancestry could be traced. For example, the Third House of Betazed was the third oldest House. (TNG novel: Imzadi)