Yes and Yes!
Yes, these designs are used for many things like cards, invitations, door magnets, etc. but the main use is to make tshirts.
Yes, making the tshirts is very easy. Simply save the image to your computer, print to the iron on - following the directions in your package and iron on.
Tips:
Be sure to use dark transfers if you are putting the design on anything but a white tshirt or all white areas of the design will be the color of the shirt.
Be sure to wash shirts before ironing - remember not to use fabric softner or dryer sheets.
Pay special attention to your directions to determine if you need to flip/rotate the design before printing.