Adhesives are used to stick things together. Many adhesives occur in nature and have important uses for plants and animals. What makes glue, paste or tape stick to things? Wood, paper and many other materials have tiny cracks and holes in them. When we glue things together, sometimes the glue seeps into the tiny openings and hardens, making the materials stick together. Other times, the molecules on the surface of an object get tangled up with the glue molecules, making the objects stick together.