Host-Guest Chemistry is a field of chemistry that studies the interactions between a host molecule and a guest molecule. The host typically has a specific structure that allows it to encapsulate or bind the guest, leading to unique chemical and physical properties. This interaction can be influenced by factors such as size, shape, and chemical compatibility. These host-guest systems are important in various applications, including drug delivery, sensing, and catalysis. For example, crown ethers and cyclodextrins are common host molecules that can selectively bind certain ions or small organic molecules, enhancing their stability and reactivity in different environments.