Blu Tack is a special kind of sticky stuff that you can use to stick things together. It's a little like glue, but it's soft and squidgy, kind of like play dough. You can mold it into different shapes, stick it on the back of a piece of paper or a poster, and then press it onto a wall or a door. It's really easy to use and it doesn't make a mess. And, the best part is that you can reuse it over and over again! So, if you want to stick something somewhere, but you don't want to use glue that might make a mess or damage the surface, Blu Tack is a great alternative.