When the first TV commercial appeared announcing skin care for women over 30, did you sit up in your chair because you had just turned 30? When you first heard Levi's advertising jeans with more room in the seat and thighs, did you suspect that someone was peeking in your windows?

Have you noted all through your life, that every time you go through a stage or get a bright idea, three best sellers appear on the same subject? Is it a coincidence that your current problems are suddenly addressed in 14 different newspapers and magazines?

Do you feel on the one hand uniquely un original; your life is pop, and on the other hand, flattered by all the attention?

Does it surprise you that the mid-life crisis is on everyone's lips, just when you're experiencing strange discontents and yearnings?

And the most important question: Were you born in America between 1946 and 1964?

If so, you are -- like it or not -- a member of The Baby Boom. This factor, more than any other, has been responsible for the environment you live in.

Because of your numbers (the biggest generation in history), you had -- and continue to have -- the world's attention. Because of your buying power, every whim is indulged. Your sense of importance is reinforced constantly. Your generation has what every politician dreams of: money, media, majority.

Landon Jones, an editor of People magazine (who is not, by the way, a member of the baby boom), has gone carefully through the cherished details and ideas of your generation, from Davy Crockett hats to Adidas running shoes, from Siddhartha to Passages, and put them all together in the book, Great Expectations: America and the Baby Boom (Coward, McCann & Geoghegan, $ 15.95, or Ballantine paperback, $ 2.95).

The book has one problem: Jones has to use the phrase "baby boom," which conjures up acres of squalling infants flinging Gerber's peas and carrots at each other. You'd prefer a more elevated catchword for your life.

But if you can look beyond that phrase, Great Expectations will introduce you to a new sport, boom-watching. For the next 50 years, you'll have an idea what the greatest show on earth is all about. It might take some of the sting out of your struggles.

Here is a basic glossary of some of the terms you may hear bandied about:

Good Times Generation: The name Jones gives to parents of the baby boom. They were born between 1925 and 1940. Their numbers were fewer than the generation before them because couples were hesitant to bring children into the Depression. Because they were "the smallest percentage increase in American history," there would be an open position waiting for them all their lives. For them, life was always getting better.

Procreation Ethic: What drove the Good Times Generation to create the baby boom. In 1946, America was spacious and underpopulated. There was more money to spend than ever before and the only problem was how to spend it. The news from demographers was that we needed more babies. Every magazine, soap opera and advertisement pounded out the message. Look magazine applauded the American mother.

"The wondrous creature marries younger than ever, bears more babies and looks and acts far more feminine than the "emancipated" girl of the '20s and '30s. If she makes an old-fashioned choice and lovingly tends a garden and a bumper crop of children, she rates louder Hosannas than ever before."

Baby Boom: 1946-1964. In 1946, the birthrate jumped from 2.9 million to 3.4 million, the highest birthrate in a decade. It continued to rise for 11 years, with 1957 (4.3 million babies born) the high-water mark.

Pig in a Python: This is the picturesque metaphor that demographers use to describe the freakishly large generation -- 75 million -- moving through society. Every place they pause there is high visibility and the roar of a crowd. We try to give them names, everything from War Babies to the Me Generation, but the names won't stick because the boom keeps moving.

"As the boom generation left the preschool ages," writes Jones, "we stopped worrying about preschoolers. As the baby boom left high school, the teen-age culture lost its energy. As the baby boom left the colleges, the colleges returned to normal. As the baby boom entered adulthood, the rivers of ink that had been spilled on the subject of the generation gap seemed to dry up overnight."

Most of the prominent and most troubling issues of the past years can, claims Jones, be traced to the baby boom. Suburbia, the crunch in the schools (remember those big classes), rock 'n' roll, the rebellion over Vietnam, college unrest, inflation, unemployment, the crime wave, the housing shortage, divorce rate, liberal reforms, the singles society, the health craze.

The Spending Boom: Smiling over the bassinets of the baby boom were economists, industrialists and entrepreneurs. Among their terms of endearment: "a market growing by the size of Iowa every year."

But their changing tastes have kept business jumping: from Family Size to Single-Serving Size, from Pepsi to Perrier, from underground to alternative newspapers, from Seventeen magazine to Savvy. Even their current money worries are turning brand-name discounters into a growth industry.

The Left Out: the group born just before or during WWII. They read about their growing pains a few years too late, but they had their choice between the old world and the new. They started their careers when their skills were scarce and there was a huge generation right behind them to write about, sell to, teach, doctor and marry.

The Baby Bust: The generation that has always felt overcrowded is failing to reproduce itself. "Fertility," says Jones, "dropped to the lowest levels in American history" from 1965 to 1980. The schools built to accommodate the baby boom are struggling or closing down. Demographers are waiting for another baby boom, the result of women delaying childbirth till their 30s. But this may never happen.

The Cult of the Adult: As a result of divorce, working women and different priorities, "The baby boomers," says Jones, "have become the first generation of parents to be widely unavailable to their children." Children, notes Jones, are not an obligation to parents today but another life style to choose from.

The Superclass: The college-educated members -- blacks and whites -- of the baby boom. They are heading into the years of highest earnings. They are the professional-managerial couples with no or few children and the extraordinary privileges of their education and income.

The problems they face, say Jones and others, will be because it will be too crowded at the top. The goal of becoming a top executive may have to be adjusted or abandoned. Jones predicts more part-time work, lateral transfers, job rotations and employers offering "psychic benefits."

In politics, the Superclass will throw its voting power, says Jones, into "event" and "issue" politics based less on political ideology than on a "'What-does-it-do-for-me?' ideology."

The New Old: Growing old should be different for the baby boom than for their elders.It is doubtful that the baby boom will allow itself to be ignored, and while the current elderly represent the least-educated segment of the population, the baby boom is the best educated.

"If the generations after the baby boom continue the present trend of receiving less education," muses Jones in his book, "then the boom generation may someday have the unique destination of turning old age into the last bastion of culture and sophistication."

The baby boom will be healthier into their old age and because Social Security will be stretched beyond its limits, they will probably continue working longer.

"If the baby-boom generation continues to produce and promote innovation throughout its life-cycle, if only to find solutions to the problems caused by its mass," says Jones, "we may wind up with an entirely different notion of what life is like after 65."

This could be their greatest achievement.