Tight coupling refers to a situation in software design where different components or modules are highly dependent on each other. This means that a change in one component often requires changes in others, making the system less flexible and harder to maintain. For example, if a function in Module A relies heavily on the internal workings of Module B, any modification in Module B could disrupt Module A. In contrast to loose coupling, tight coupling can lead to increased complexity and reduced reusability of code. When components are tightly coupled, they are often difficult to test independently, which can slow down development and increase the risk of bugs. This is why many developers strive for a more modular approach, promoting loose coupling to enhance system adaptability.