A Software Development Kit (SDK) is a collection of tools, libraries, and documentation that developers use to create applications for specific platforms or frameworks. It simplifies the development process by providing pre-built components, code samples, and APIs, allowing developers to focus on building their software rather than starting from scratch. SDKs are often tailored for particular operating systems, programming languages, or services, such as Android, iOS, or AWS. By using an SDK, developers can ensure their applications are compatible with the platform and can leverage existing functionalities, ultimately speeding up the development cycle and improving software quality.