What is the use of Product Properties in Product Family

Dear all,

I just try to think of an organisation of my product based on product family. Then I have seen that we can assign product properties for a product familly.

What is the exactly used of those product properties in a product family ?

Does it appears somewhere when creating a quote or does it affect something and at which phase are they selected or change by user ?

For instance I have different range of touch screen based on size like 32", 42" and 55". Each of this product is corresponding to a unique product for each screen size. When I create product familly called TOUCH SCREEN, I then start to add a SIze as Properties, but when I assign each screen product to familly, the size has no meaning as the product itslef identify a size.

Any clarification of property use will be helpful

regards