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+Although ClassiCube strives to be as platform independent as possible, in some cases it will need to use system specific code
+
+For instance:
+* Texture creation for 3D graphics rendering
+* Buffer allocation for audio output
+* High resolution time measurement
+* Window creation
+
+For simplicity, related system specific code is grouped together as a Module (e.g. `Audio`), which can then be implemented using a backend (e.g. `WinMM`, `OpenAL`, `OpenSL ES`, etc)
+
+#### Note: By default, ClassiCube automatically selects the recommended backends for the system. <br> It is recommended that you do *NOT* change the backends unless you know exactly what you are doing.
+
+However, on some systems there are potentially multiple backends for a Module. For example on Windows:
+* OpenGL could be used instead of Direct3D 9 for the 3D rendering backend
+* SDL could be used instead of the native WinAPI for the window backend
+
+TODO finish this
+
+TODO introduction (explaining platform specific modules, and how classicube has to integrate with one of them)
+
+There are two ways of changing the backend that gets used for the system:
+1) Changing the defines in `Core.h`
+2) Adding `-DCC_BUILD_MANUAL` to compilation flags and then manually defining module backends via additional compilation flags
+
+When manually compiling the source code, 1) is usually the easiest. <br>
+For automated scripts compiling every single commit, 2) is the recommended approach
+TODO: Move this into table
+
+
+### 3D Graphics backends
+* CC_BUILD_D3D9 - Direct3D 9
+* CC_BUILD_D3D11 - Direct3D 11
+* CC_BUILD_GL - OpenGL
+
+The OpenGL backend can be further customised:
+* CC_BUILD_GL11 - (must also have CC_BUILD_GL defined)
+* CC_BUILD_GLMODERN - (must also have CC_BUILD_GL defined)
+* CC_BUILD_GLES (must also have CC_BUILD_GL defined)
+
+### OpenGL context backends
+* CC_BUILD_EGL
+* CC_BUILD_WGL
+
+### HTTP backends
+* CC_BUILD_CURL
+* CC_BUILD_HTTPCLIENT - custom HTTP client
+* CC_BUILD_WININET
+* CC_BUILD_CFNETWORK
+
+### SSL backends
+* CC_BUILD_SCHANNEL
+* CC_BUILD_BEARSSL
+
+### Window backends
+* CC_BUILD_SDL
+* CC_BUILD_X11
+* CC_BUILD_WINGUI
+
+### Platform backends
+* CC_BUILD_POSIX
+* CC_BUILD_WIN
+
+TODO fill in rest
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