The is a unique identifying number for this
Household or
Organization.
While every type of record in the database will have it's own ID number (for example each gift will have a unique ID number, every email address will have a unique ID number) which will be unrelated to any other ID number in the system, only this Master ID number will ever be important. It is the primary ID number that all data attached to this
Household or
Organization will use to attach themselves. If you have a Membership program, this would, by default, be their Member number. When you run a
Mailing List, this number is always sent along with the list so we always have a way to relate the data you took out to the data in the database.