Talking about background checks for gun purchases involves so many acronyms it starts to look like alphabet soup. Here are a few crucial terms: DROS: Every gun purchase in California -- whether from a licensed dealer, a gun show or a private party -- requires a Dealer Record of Sale. The $19 DROS fee covers a background check and transfer registry. FFL: A Federal Firearms License lets a person or company make or sell guns. Under the Gun Control Act of 1968, the FFL system effectively banned the direct mail order of firearms (other than antiques) by consumers. Instead, it required that anyone who wants to buy a gun from someone other than a private individual must do so through an FFL holder. That same law also banned those without FFLs from buying handguns outside their state of residence. HSC: California requires that anyone buying or otherwise taking possession of a handgun first earn a Handgun Safety Certificate, obtained by passing the state Justice Department's test administered by a state-certified instructor. To take the exam, a person must be 18 or older, provide proof of California residency and pay a $25 fee. An HSC remains valid for five years. NICS: The National Instant Criminal Background Check System is a computer network used by Federal Firearms Licensees to instantly determine whether a would-be buyer is eligible to purchase firearms. Linked to various local, state and federal databases, NICS is meant to raise the alarm if a potential buyer has ever been convicted of, or is under indictment for, a crime punishable by a year or more behind bars; is a fugitive; abuses any controlled substance; has been judged by a court to be mentally defective or has been committed to a mental institution; is in the United States illegally; was dishonorably discharged from the armed forces; has renounced U.S. citizenship; is under a restraining order for having harassed, stalked or threatening an intimate partner or such a partner's child; or has been convicted of misdemeanor domestic violence. NICS is at the FBI's Criminal Justice Information Services Division in Clarksburg, W.Va., and is available 17 hours a day, seven days a week, including holidays (except for Christmas). PFEC: If you want to check whether it's legal for you to own a handgun in California before you try to buy one, you can fill out a Personal Firearms Eligibility Check Application form, have it notarized and send it to the state Justice Department with a $20 fee. Results are sent by mail; allow 90 to 120 days.