It’s important to plan not only your keyword list but also the hierarchy of keywords, using a controlled vocabulary of keyword categories. The keyword list can be edited in the Keyword Tags panel by dragging-and-dropping the keywords in whichever way suits your needs best and at any time you want. You can even have several tiers of subcategories. For example, you could organize place name keywords in the following order: Places > Country > State > City. When you’re working in the Keywording panel, you can enter new keywords and assign a hierarchy by including an angle bracket (>) character after the keyword, followed by a category. So if you wanted to add a new keyword called Elephants as a subcategory of Animals and Nature subjects, you would type Elephants > Animals > Nature subjects. When you press the E key, you’ll see the Elephants keyword appear as a new subset keyword in the Keyword Tags panel as well as listed in the Keyword Tags section of the Keywording panel.