Attributes are features or characteristics which are used to differentiate an entity from other entities. Values can be assigned to these attributes. These values can be either numeric or non-numeric. E.g. ‘Student’ is an entity. Its attributes can be roll number, name, date of birth, gender and class. The values for these attributes can be 1234, Ritika, 19/11/1982, female and MCA.

Domain is the set of values that can be assigned to an attribute. We can assign values to the attribute only from this domain and we can not assign any value which is outside this domain. Thus domain fixes a boundary. E.g. Gender is an attribute. Its domain contains two values: male and female. So we can assign only male or female to gender attribute and no other value.