Weight: Paper thickness is measured by weight. The higher number you see, in pounds, on the packaging label, the thicker your paper is. This doesn't mean you have to find the thickest paper you can—most card stocks are a great weight for invitations and can hold up to being mailed.
Tips For PUTTING IT ALL TOGETHER _ Paper cutting: The Internet loves to tell you that if you are doing your own DIY wedding invitations, you need to invest in a professional paper cutter, or at least a rotary cutter, along with a tape gun, and the list goes on. You can skip this by ordering paper that's cut to size—always double check to make sure you can print said format of course—and skipping any taped on embellishments. I promise, a fancy invitation need not have three layers of cardstock and the ability to stand on its own.