From their FAQ:What is Twig?
Twig is a platform where you can see photos of what people on twitter are wearing — right now! The photos are organized by brand, so that you can easily browse through all photos of people wearing brands you like.
When you’re trying stuff on at the mall or at home, or just wearing an outfit you want opinions on, Twig is the best and easiest way to get immediate feedback. When you post your photo using Twig, not only will you get feedback and views from your followers, you’ll also have the Twig community telling you what they think!