It is considered best practice to learn the following basic concepts before you start building:
- Platform
A combination of development boards and kernels. Supported subsystems and components vary with the platform.
- Subsystem
OpenHarmony is designed with a layered architecture, which consists of the kernel layer, system service layer, framework layer, and application layer from the bottom up. System functions are developed by the level of system, subsystem, and module. In a multi-device deployment scenario, you can customize subsystems and modules as required. A subsystem is a logical concept and is a flexible combination of modules.
- Module
A module is a reusable software unit that contains source code, configuration files, resource files, and build scripts. A module can be built independently, integrated in binary mode, and then tested independently.
- GN
Generate Ninja (GN) is a system used to generate build files for Ninja.
- Ninja
Ninja is a small high-speed build system.
## Working Principles<a name="section193961322175011"></a>
The compilation and build process of OpenHarmony is as follows:
- Parsing commands: Parse the name of the product to build and load related configurations.
- Running GN: Configure the toolchain and global options based on the parsed product name and compilation type.
- Running Ninja: Start building and generate a product distribution.
## Building a Mini or Small System<a name="section119041639115811"></a>
See [build\_lite](https://gitee.com/openharmony/build_lite/blob/master/README.md).
## Building a Standard System<a name="section8750514195912"></a>