What is a trim on a phone case? (iphone)?

So i'm trying to pick out what case i want for my iphone 5, it's white, and the options include choosing what color "trim" i want for the case. & it's either black trim or white trim. This is the case i've been looking at http://www.carved.com/emily-jane-flower-fade-iphone-5-5s-case.html
since my phone is white I would think that a white trim might look better but i'm not even sure what a trim is so can someone advise me on this?

Trim is referring to the edges.