Final answer:
A null value is the default value that a field assumes unless an explicit value is entered. It represents the absence of data or unknown information in a field.
Step-by-step explanation:
In the context of databases, a null value is a value that represents the absence of data in a field. It is the default value that a field will assume unless an explicit value is entered. Null values are commonly used to indicate missing or unknown information.
For example, let's say we have a database table for student records. Each student has a field for their birth date. If a student's birth date is unknown or not provided, the field can be assigned a null value.
Null values allow for flexibility in data storage and querying, but they also require special handling in programming and database operations.