Essential Oils

When my frontier woman was talking recently she mentioned Essential Oils.  My mind immediately went to 5w-30 motor oil, 90w gear oil and of course Rem-Oil for guns.  Imagine my shock that she was referring to something entirely different. 

"Essential oils are concentrated, liquid plant extracts used for therapeutic and medicinal purposes."

What on earth make them "essential"?  Essential means "absolutely necessary; extremely important".  I don't seem to "need" liquid plant extracts.  My car does however, "need" various oils as do my guns.  

Attempting to be open-minded I visited Rocky Mountain Oils to see what is going on.  Here is what they say:

Rocky Mountain Oils Starter Kit

Every home needs a diffuser,

at least one carrier oil,

a roll-on bottle and a how-to guide. 

What the ...?  So every home needs these items?  In addition they say you can build your own kit that included:  Lavender, Tea Tree, Peppermint, Frankincense, Lemon, Helichrysum italicum, Immune Strength and Purify.  OK, there must be some thing more about this.  Why does each home need these oils?

I checked another EO (that's short for essential oils) web site and saw this warning under safety:

"Each bottle of Young Living essential oil is labeled with directions for how that oil can be used, and these directions vary based on location."

Now I am confused.  Based on what location?  What difference does it make if I live in Washington or New York?  So my wife sees my confusion and lets me know that location means where on your body.  A bit farther down the list of safety topics is "Can essential oils be applied to sensitive areas?"

The answer to that question includes this "recommends that you avoid contact with EOs and sensitive areas such as eyes, ears, genitals and mucous membranes."

I am back to my original question What on earth makes them "essential"?