An SDK, or software development kit, is a set of software development tools provided by hardware and software vendors that developers can use to build applications. An SDK typically includes a compiler, debugger, and sometimes a software framework, and can take the form of APIs in the form of on-device libraries of reusable functions used to interface with a particular programming language, or it may be as complex as hardware-specific tools that can communicate with a particular embedded system.
SDKs provide pre-built modules, components, packages, and tools for developers to build, test, and deploy software applications. They simplify developing, testing, and integration with other systems and services, code samples and tutorials, debugging tools, and code libraries. SDKs can also help developers build more complex app features, such as augmented reality and virtual reality, and add new features.
In contrast, an API, or application programming interface, is an interface for a service. APIs provide a way for different software components to communicate with each other, and they allow developers to access the functionality of a service or application without having to know how it works.
Overall, an SDK is a set of tools that developers can use to build applications, while an API is an interface that allows different software components to communicate with each other.
