Signing our name is the result of such practiced consistency that we rarely stop to think about it. Checks, credit card slips, leases—documents of all kinds require our unique stamp of approval that lets others know we’re on the same page. Here are a few things to consider the next time you put pen to paper, according to Columbia Law School professor Ronald Mann.

1. SIGNING IS NOT ALWAYS NECESSARY.

Don’t think that forgetting to sign your credit card slip before you leave a restaurant is going to open up a debate about your responsibility to pay. “A common contract is just an agreement between both parties,” Mann says. “You agreed to pay when you gave them your card.” All a signature really does, he says, is make it less likely for you to claim you didn’t consent to the deal later on.

2. NO ONE REALLY EXAMINES YOUR SIGNATURE ON A CHECK.

Computer automation has largely removed any human inspection of a personal check to make sure the signature is that of the checking account’s owner. In the event your checkbook is stolen, it’s far more likely that foul play will be noticed because of what a thief might use it for, not because he or she doesn’t know how to sign your name. “People tend to write checks in patterns,” Mann says. “You might use it just to pay a babysitter. If you suddenly write a check for $200 in groceries, it’s going to be a break in the pattern.”

3. IT’S PARTLY PSYCHOLOGICAL.

Because not every agreement requires a signature to be enforceable, Mann has found that some entities request it because it can deliver a more profound message of commitment. “In your mind, you’re really agreeing to something when you sign,” he says. “You’re not as likely to disavow the agreement.”

4. YOU DON’T HAVE TO SIGN YOUR CREDIT CARD, BUT…

…don’t expect your lack of signature to be a remedy if your card is stolen. The idea behind not signing a card is so a clerk will ask for identification. (Some people will even put “Check Photo ID” in the signature space.) No thief would have a driver’s license bearing your uncanny resemblance, right? But here's something equally unlikely: the clerk bothering to ask in the first place. “I haven’t signed a credit card in 15 years, and someone asks [for ID] maybe once a month,” Mann says, an experience that echoes that of many no-sign devotees.

5. YOU MIGHT HAVE TIME TO BACK OUT.

For mortgage refinancing and other large transactions, a signature is more than a formality: It indicates a binding agreement. But in many areas, consumer protection laws give the signee three days to change their mind and essentially revoke their signature. While highly state-dependent, the right of rescission might come in handy when second thoughts arise. Additionally, the Federal Trade Commission (FTC) has a Cooling-Off rule fit for sales completed in your home or at a temporary location. (Goodbye, time share.)

6. THE COLOR OF THE INK MATTERS.

But just a little. “Lawyers like blue ink, so they can tell an original from a copy,” Mann says. But in most cases, no one is going to dispute a contract signed in black, red, or even pink.

7. CO-SIGNERS ARE BORROWERS.

A surprising number of parents, spouses, and friends volunteer to co-sign for a car loan or other major purchase without fully understanding their responsibilities. The lender will not only hold you financially responsible if the borrower fails to pay, they’ll also be reporting it as a debt to your credit agencies. And in some states, the lender can treat a default by coming to you for payment first. Make sure you understand that “co-sign” means “co-borrow.”

8. YOU REALLY CAN JUST MAKE AN “X.”

All a signature is expected to do is signal that you intend to adopt an agreement, whether it’s a purchase, offer of employment, or business transaction. To that end, making a big “X” on the paper or drawing a symbol does the job just fine. “It doesn’t have to be consistent with your signature,” Mann says. But the other party is under no obligation to accept your smiley face without concern. “If they have a tape of you signing, that might be okay. But if it’s too unusual, they might get worried.” Could you blame them?

All images courtesy of iStock.