What exactly is a Baby Boomer?

I found this definition at Baby Boomers Headquarters.com http://www.bbhq.com/

" Stated very simply, the demographers, sociologists and the media define baby boomers as those born between (and including) 1946 and 1964. (There is no law or constitutional amendment so stating; and other boundaries have been suggested. But this is the time frame most commonly used.) In 2007, that would make us between 43 and 61 years old. There are about 75 million boomers in the U.S.; we currently represent about 29% of the U.S. population. (In Canada, we are sometimes known as "Boomies"; there are 6 million of us there. In Britain, our generation is known as "the bulge.")
The term is used (nobody knows who coined the phrase) to define the "boom" in births after WWII. Our Boomer Stats page identifies the number of U.S. births during the 40s, 50s and 60s.
The 1960s is the decade that defined the boomers. The music, events, and the social changes made a permanent impression on us. Those of us born during the "peak" boomer years, '52-'57, were in our formative years during the sixties. There were so many changes in the sixties that how old you were during the decade greatly affected how you turned out. 1961 was a whole lot different from 1969!
Those born at the early end of the spectrum were in our early 20s by 1970. The deaths of President Kennedy, Bobby Kennedy, and Dr. Martin Luther King; the Vietnam war and related protests; and the Watergate scandal... all made deep impressions on us.
At the other end, those born after 1959 have no direct recollection of the assassination of President Kennedy; they were not yet listening to rock music by the time the Beatles broke up. They were much more likely to use illegal drugs.... often to a great and disturbing excess. And they were never subjected to the military draft. So any attempt to lump us all together probably won't work. We can tell, by the e-mail we receive here at BBHQ, that there is much that ties us together, but also much that separates us.
Our e-mail indicates that many of us are committed to marriage and are still happily married to our high school sweethearts. And many of us have been married and divorced... more than once. We are the generation that pushed the divorce rate up to 50%... and made it seem "normal" and thus acceptable.
Many of us went to work for a company, worked our way up the ladder, and are now enjoying the fruits of our labors. We will retire in a few years, and live a life of leisure, or embark on a second career. But many of us are entrepreneurs, and have never worked for a big company. Many of us plan never to retire."