Book excerpt: Crown Ethers and Cryptands introduces the broad and basic principles of crown ether and cryptand chemistry at the advanced undergraduate, graduate and working professional level. The book provides a brief introduction, outlining the history of the field and goes on to cover syntheses, complexation of cations and molecules, complex structures, applications and recent developments. It aims to acquaint readers with the scope and principles of the field, providing a bibliography of reviews and books as reference to further reading and citations of the original literature.