Structural patterns are design patterns that focus on how objects and classes are composed to form larger structures. They help ensure that if one part of a system changes, the entire system doesn't need to change, promoting flexibility and reusability. Common examples include the Adapter pattern, which allows incompatible interfaces to work together, and the Composite pattern, which lets clients treat individual objects and compositions uniformly. These patterns are essential in software development as they provide solutions to common problems related to object composition. By using structural patterns, developers can create systems that are easier to manage and extend over time, ultimately leading to more maintainable code.