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Using credit cards online: is it safe?
You're right that someone who, say, photographed the front of your card at the store could use it to make some online purchases. Schemes like Visa's 3-D Secure provide additional online security by having you enter your password on the issuer's website, but they aren't common yet in the US. But as littleadv says, you as the cardholder generally aren't liable for fraud (except $50 in some cases). Just be sure to check your statement monthly and notify the issuer of any fraud within 60 days. To issuers, fraud losses are fairly predictable, and the cost is acceptable.