(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who.
First off, you will most likely find a variety of tools to include in your toolbox, depending upon the intended outcome you are expecting. It is possible to add metadata with special software. There are other well-known applications such as Adobe's PhotoShop, Lightroom, or Elements to name just a few. In addition, there are many others created by independent app creators.