A Software Development Kit (SDK) is a package of tools, code libraries, and resources designed to simplify software development for a specific platform, framework, or device. It provides pre-built functions to help developers build applications tailored to that platform, making it easier to access and use the underlying APIs of the platform they are designed for. On the other hand, an Application Programming Interface (API) is a set of rules that allow different software applications or services to communicate with each other, defining how they can exchange data and perform functions. While both SDKs and APIs are used in software development, they serve different purposes: SDKs make it easier to use APIs by providing wrappers around them, offering type safety, error handling, and automatic retries, whereas APIs expose a service to your internal infrastructure or the world via the internet, allowing developers to build applications that integrate with those services. By choosing between SDKs and APIs, developers can decide whether they need a wrapper around an API or direct access to it, depending on their specific use case and development requirements.