Have you ever picked up a pattern and noticed the word "underlining" and wondered "what is that?  Is lining and underlining the same thing?"  This answer is found in this tutorial.  While lining and underlining can serve a similar function, they are not necessarily the same thing and there are differences in how they are integrated into a garment.  We cover what underlining is used for and then how to sew it to your garment.  Even if your garment doesn't specifically request underlining, you'll still be able to use your new found knowledge to transform a garment to accommodate this detail.  Underlining is not only functional, but it allows you to expand the type of fabrics you can use, to include sheers or lace, and add an extra element of contrast and interest.