SDKs are pre-built, reusable collections of libraries, APIs, documentation, utilities, and sample code that facilitate the implementation of specific features or entire applications without requiring developers to build them from scratch. An SDK can be seen as a "kitchen" with various appliances, whereas a library is like a stove that performs a single function, and a framework is akin to the overall structure of the house upon which other components are built. By understanding the differences between these terms, developers can make informed decisions about which tools to use and when to build high-quality mobile apps.