A TIF is simply a compressed image, much like a JPEG. TIFs however, are lossless. They don't exhibit the weird smudgy pixels or "artifacting" that JPEGs do. I've found TIFs to be smaller files, taking up less hard drive space.
You can open TIFs in any image editing program, even Microsoft Paint on PCs or Preview on Macs. If you need a different file format to send to a print shop or upload to a website, simply choose File > Save As and save the image as the required file type. Your download also includes PDF files of all elements, which are widely accepted by print shops.
I use TIFs in my digital downloads because they are lossless, high quality files. My priority is making sure my customers always have images of the highest quality to work with and print.
As always, please feel free to contact me if you have any questions regarding Paper Cut Club products. I will walk you through absolutely anything I can.