SDKs are software development kits that provide a higher level of abstraction, making it easier to interact with APIs, hardware, or other software using preferred programming languages. They speed up application development by handling boilerplate code and implementing best practices. SDKs come in various types, including API, Hardware, Mobile, and UI SDKs, each serving specific use cases such as payments, analytics, social media integration, and custom relationship management. A good SDK should be easy to install, have well-documented code samples and tutorials, support idiomatic programming languages, have few dependencies, be simple to use, and be up-to-date with the latest API or hardware versions. By using a good SDK, developers can improve their experience and build functionality into applications without writing all the code themselves.