This book sets out to describe the importance of adhesion in our Universe. Although we believe that the universe is expanding and flying apart, we can also see that the Earth and its parts are sticking together with great tenacity. Gravitation explains part of this attraction on earth, but is insufficient to explain why adhesives stick jumbo jets together or why our bodies do not fall apart. To understand the strong attractions between earthly matter we must introduce the idea of molecular adhesion; the fact that all molecules attract each other with a considerable force. This idea at first seems paradoxical because we can identify situations where adhesion is very strong, for example when paint sticks to a surface, but we can also see cases where adhesion is very weak, when sand flows through an hour glass. The objective of the book is to provide explanations for these apparently perverse effects.