It is not only important to know how to do things but why. This is an effort to give some history and the reasons why things are the way they are.
If you know only how to do something by following steps 1, 2 and 3, but step 2 fails, you might be stuck. If you know why you are doing the steps you may be able to adjust to the issues presented to you.
These are being written and will appear when ready.