WASHI TAPE

To put it simply, washi tape is a high quality masking tape made of rice paper. 

But more than that, washi tape is a material which is beautiful yet useful at the same time. You can tear it, stick it, reposition it, write on it... The low tack adhesive makes it extremely easy to use (and reuse). I think it is so popular because it is so easy to use - and looks good while doing it!