Education

Generally, here in the states it is undergraduate (a typical 4-year study), followed by masters degree (an additional 2 years), and finally PhD (Piled Higher & Deeper).

Postgraduate would be additional research beyond the undergraduate studies and would include masters and/or PhD degrees. Postgraduate is also known as graduate.

If it doesn't make sense, then it might be by design just to add mystery to the whole idea of higher education.

The thought process goes like this, "I am confused as to the meaning of undergraduate, graduate, and post graduate work, but I am too embarrassed to ask." This leads to the pursuit of higher education in the vain hope that it will be explained somewhere along the 12 years that you toil away in search to the meaning of it all. After completing your PhD there is a short time of euphoria as you mentally pat yourself on the back for your achievements. However, afterwards you realize that the original quest that drove you through 12 years of hell has remained entirely elusive and unresolved leaving a vast hole in your life, which leads to one more question, "Why?" Unfortunately, your peers seem to ignore the whole question, probably because they do not know themselves.

Realizing there is no place to turn you are forced to stop shaving and changing clothes and hang out on dark street corners, drinking out of brown paper bags, and large cardboard boxes become your most trusted friend.

In the US, undergraduate courses are those you take before "graduating" basic four year college. Hence "under" graduate. Generally, graduate courses are those you take after graduating and can lead to a Master's or PhD. Postgraduate courses are normally those that you take after obtaining a Master's or PhD. It's more than a little confusing. "PostDoc" is a term often used used for educational work you do after your PhD, and is another term for postgraduate education.