A History of Your Social Life--From A to Z : Keepsakes: The address book is better than a diary, better than a scrapbook. It triggers memories, but spares anyone the embarrassment of viewing their senior prom photo.

Life is a lot like a cross-country road trip: As you go along, you’re always looking for signposts to show you’re getting somewhere. The problem is finding a reliable indicator of where you are and how you got there.

You could try a diary, but who really has time to write in one, let alone go back and read about your crush on your ninth-grade math teacher? Photo albums are another option, but it’s awfully embarrassing to see that lime-green leisure suit you wore for your senior picture. Parents might be helpful, but with any luck they don’t know about the good stuff.

That leaves only one effective tool for putting your life into perspective. It’s a document that reminds you who your friends are and triggers more fond memories than a year of looking at photo albums. It’s your social history in printed form. It’s the almighty address book.

“I think it’s the bible,” says George Shamma, a Los Angeles-based contractor who has more than 900 names in his. “I’ll look through it sometimes and just reminisce. It’s like a scrapbook of my life.”

Think about it. You wouldn’t put somebody in there if you didn’t like that person. If you had a pleasant childhood with lots of friends, there will be names in the book to reflect that. If your college years were the time you established lifelong bonds, it’s in the book. Few belongings are more personal.

“I once had a friend who wanted a phone number that I had and he went into my book without asking,” Shamma says. “He is no longer allowed in my house.”

Perhaps it’s no coincidence that many people start an address book at about the same time they hit puberty. It’s a sign of growing up.

“I tried to do it when I turned 14, to imitate my parents, I guess,” says John Horton, a San Francisco lawyer.

It’s usually not a formal book at that age, just some notebook paper with friends’ phone numbers scribbled down. An official book, usually in the form of a Daytimer, comes when you reach adulthood and begin accumulating friends. At which point, you face the first of many key address book decisions: pen or pencil?

On one hand, pen implies permanence. This is a friend you’re confident of, one who is going to stick with you for a long time.

“I always use a pen to make entries,” Shamma says. “I can always shove more pages in my book. And I normally wouldn’t even put somebody I’ll deal with one or two times in there.”

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On the other hand, pencil may indicate a more temporary friendship, one that can be eliminated with one swipe of an eraser. But it can also just be a sign of a friend who moves too much to merit an inked address.

Michelle Hunt, a Los Angeles publicist, writes relatives in pen because “they’re not going anywhere,” but enters friends in pencil because “they’re young, and they may move around a lot.”

Figuring out how to write people into your address book is critical, but it’s still secondary in importance to determining who makes it in. The way you make that decision is another good indication of what sort of person you are.

For instance, there are the collector types. Hunt has about 200 names in her book, including everyone from college pals to ex-boyfriends to friends of her family. Her standards for admission are pretty simple.

“If I talk to someone at their home and they talk to me at my home,” she says. “And if I talk to that person at night or on a weekend, that constitutes a friendship.”

As at a roach motel, though, most who check in to her address book never check out.

“But there’s always the chance I’ll see somebody on the street and wish I had their number, or I’ll be reading something funny and it will remind me of a college friend,” Hunt says. Hence, her list has very little movement.

Then there are those who are a little more demanding.

“Most people initially go into my Rolodex,” explains Lisa Desantis, a Los Angeles-based banker whose book has about 150 names. “You have to build up to the address book. It can take a good year to make it in.”

Quality of time spent with someone, not just the quantity, have something to do with who you let in as well.

“You don’t have to know me long for your phone number to make it in,” says Horton, whose book contains nearly 100 entries, about half of whom he just keeps a phone number for since they live locally. “There’s a woman in here I’ve only been on three dates with. But if you make an impact, you get in. And old girlfriends tend to stay in even if we lose touch. It’s a sentimental thing.”

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There’s also a fine line between business and personal entries. Hunt’s address book is filled with the names and numbers of business contacts she might need over a weekend, and 700 of the 900 names in Shamma’s are work-related.

“I’m more picky about who gets in on the friend side,” he says. “I may add one name a month there, but sometimes in business I’m adding one or two people a day. I think I put more effort into searching (friendly entries) out.”

Getting in is one thing. Getting booted out is quite another. It’s the ultimate statement that you’re making a change in your life, that you’re in control of your destiny.

“It’s like the movie of my life,” Shamma says. “I decide who gets in and who doesn’t.”

Seldom do you just fire somebody already cast in your picture. Rather, the real decision comes when it’s time to get a new book. It’s a chance to take stock of this list of people and determine who you can do without. There are plenty of reasons to have a falling-out with a friend, but generally there is only one good reason to let them fall out of your address book: You seem to have fallen out of theirs.

“If I haven’t talked to somebody in a year, they might be out,” admits Desantis, although she hedges a bit by keeping her old address book in a drawer. Just in case.

“If I can’t get ahold of you four or five times in a row with the phone number or address I have, you’re out,” concurs Shamma. “I’m pretty arbitrary about it. And sometimes I’ll end up seeing somebody I’ve dropped and I’ll go up and tell them they’re out. It’s a good icebreaker.”

It’s no big deal. You’ve gone five years without writing to or hearing from a college roommate or ex-girlfriend, so it should be pretty painless to leave his or her name out of a new address book. That leaves all the more room to make new friends who will stay in touch. Still, because your book is like your permanent record, making a change is tough.

“I feel guilty,” Horton says. “You don’t like to just drop people out of your lives like that. And on days when I’m feeling bad, I like to start with the A’s and just look through the whole book to feel better.”