The @types/supertest package provides TypeScript definitions for SuperTest, a high-level abstraction for testing HTTP. Its primary use is to simplify testing Node.js HTTP servers. By installing this package, TypeScript users gain static typing and autocompletion when using SuperTest in their projects. This enhances developer experience and reduces errors, especially when working with complex APIs and response structures. These definitions ensure type safety and provide a seamless integration with TypeScript projects, preventing runtime errors related to incorrect type usage.