A software development kit (SDK) is a collection of software tools and libraries that developers use to create applications for specific platforms or frameworks. SDKs typically include APIs, documentation, code samples, and development environments, streamlining the application development process. By providing standardized protocols and tools, SDKs help developers leverage the functionalities of a platform, ensuring compatibility and efficient integration. Using SDKs can significantly reduce development time, lower costs, and enhance the quality of applications by providing out-of-the-box solutions for common programming challenges.