Final answer:
Cardinality specifies the minimum participation degree of one entity in a relationship with another, and it is represented in ER diagrams through notations such as Crow's Foot.
Step-by-step explanation:
The concept you are referring to is known as cardinality, which in the context of database systems, specifies the degree of minimum participation of one entity in the relationship with another entity. In other words, it indicates the number of instances of one entity that can or must be associated with each instance of another entity in a relationship. Cardinality is commonly expressed as 'one-to-one', 'one-to-many', or 'many-to-many'.
There are two types of cardinality constraints: minimum cardinality and maximum cardinality. The minimum cardinality can be zero (optional participation, where an entity does not have to participate in the relationship) or one (mandatory participation), whereas the maximum cardinality could be one or many, indicating the upper limit of the relationship. When designing an entity-relationship (ER) diagram, these cardinality constraints are depicted through various notation systems, like the Crow's Foot notation, to visually represent database schemas.