Expressions in NX are arithmetic or conditional fomulas that let you control relationships between features in a part or parts in an assembly. For example, you can express the thickness of a bracket in terms of its length. If the bracket length changes, the thickness automatically updates to reflect that change.
You can use expressions to define and control many dimensions of a model, such as dimensions of a feature or a sketch.
In this NX Quick Tips video, I'll show you how I use Attributes and List Expressions to change a part.