Hi!
I had a couple of years training in classical singing and my two teachers (a young woman and the other an English man) never used the term "head voice". It seems to be an old term and moreover, a little confusing.
See this article:
http://en.wikipedia.org/wiki/Head_register
I am Tenor and as such I sing from the lowest note I can get (about a G under the staff to something around A sharp. (I am not very good, yes). After this register, I can continue to higher notes using Falsetto. For women it is probably different, apart from the range of course.
Note that falsetto (at least in men) is not used only beyond the range attainable in the normal register, but also (and frequently) in lower pitch notes when one need to sing pianissimo or the like.
I sing in a choir and the tenor chord uses this technique from about upper E up to where needed (classical choir music seldom goes over upper G).
Hope this helps.
I've learn quite alot by myself stuff though like the chest, mask and of course head voice and falsetto which leads me to my question....How do you know which is head voice or falsetto? I've been praticing with some Sarah Brightman and Chloe Agnew songs and learning from two programs called "Sing like a Star" and "Vocal Realese" and in one of those programs it said to be careful not to get the head voice confuse with falsetto and I started to wonder if thats what I've been doing all along. How would I know?? I feel like there is some power when I sing maybe an easier question is whats the difference between The Head Voice and Falsetto??