Value Object
In plain terms
An immutable object defined by its attributes, not identity.
Going deeper
A value object represents a concept by its values (like money or a date range) and is interchangeable when equal, with no unique identity. Two equal value objects are the same.
Under the hood
Immutable and compared by value; reduces bugs and clarifies the domain in DDD.
Examples
Money, coordinates, date ranges, DDD, immutable domain types.
Think of it like...
Like a $10 bill, any one is as good as another; only the value matters, not which note.