A brief introduction to the Real Time-Thread (RT-Thread) kernel, starting with the software architecture to explain the composition and implementation of the real-time kernel, introduces some RT-Thread kernel-related concepts and basic knowledge for beginners, so that beginners have a preliminary understanding of the kernel. The kernel library is a small set of C library–like function implementation subsets to ensure that the kernel can run independently. Real-time kernel implementation includes object management, thread management and scheduler, inter-thread communication management, clock management, memory management, etc. The RT-Thread kernel is designed with the object-oriented method. The system-level infrastructures are all kernel objects such as threads, semaphores, mutexes, timers, and so on. Kernel objects fall into two categories: static kernel objects and dynamic kernel objects. RT-Thread uses the kernel object management system to access/manage all kernel objects.