(A very good overview is also contained in the v9 help, to be found in Distrib\Help\Ai_Man_v8.chm).

In the beginning - when it was just the Salvation engine - almost everything needed to be patched: the engine offered a collection of modules, each specialising in a very small task, and the operator/programmer had to combine them in a meaningful way, to acchieve what he had in mind - play a video, map an image to a structure, control some parameters. A good part of the development over the last years is that many of everydays tasks are now packed into a fancy GUI, and are available with just one click. However, if something special needs to be accomplished, or some particular thing is not (yet) available via the GUI, patching might be the way to go. And honestly, after you have made the first steps, it is pure fun (after the desperation has vanished, that is).

Currently there are some entry points into the world of patching:

• the purest approach is the File/New menu in the Ai menu bar on top of the GUI display - this opens just a blank patch file
• the mightiest way is clicking Stage Patch: Open button in the little Ai root window. This opens a patch window which is actually the current project, with some modules and subpatches. Personally I prefer this as entry point - but you must know that you can easily render your system completely useless here.
• a more fancy way is calling the Stage Patch page from the Ai diamond in the bottom-right corner - click this, then click the stylized single DVI connector (outputs), and then the stylized wired modules (Stage Patch). This again opens the Stage Patch but in a more stylish view: you can zoom in and out (with Ctrl + and Ctrl -), entering a subpatch opens this neatly animated, and in order to ascend again you have the breadcrumps on top. It's up to you which way you prefer.
• and a special one: even all the tiles on the performance page are, down in their heart, small patches. Hence, if you right-click a tile to edit its properties the Cell Properties window to the left shows the button Edit As Patch. Clicking this opens a patch window with the modules assigned to this particular cell.