Host-guest systems are molecular structures where one molecule, known as the host, encapsulates or interacts with another molecule, called the guest. This arrangement can occur in various forms, such as in cavitands, molecular cages, or zeolites. The host provides a specific environment that can influence the properties and behavior of the guest molecule. These systems are significant in fields like chemistry, materials science, and biotechnology. They can be used for applications such as drug delivery, where the host protects the guest until it reaches its target, or in sensors, where the interaction between host and guest can signal the presence of specific substances.