People often ask me about our castile soap. The first thing they ask is, “How do you pronounce it?” In English, it is pronounced, (cass – teel’). The second thing I’m asked is, “What is a castile soap?”
Castile soap is made with just olive oil (as the oil portion). It is one of my pet peeves when people call soaps that are made with any combination of vegetable oils, “castile”. This is wrong because it gives people a false understanding of how wonderful real castile soaps are on the skin.
Castile soaps are amazingly gentle, so gentle in fact that it is the soap we used on our newborn girls. (Newborn boys could use it too, we just hadn’t made it before Hewitt was born). 
I wrote an article for GMSU on castile soaps. You may want to check it out as it has some extra information.
PJ