It can happen in seconds.

A man checking his e-mail gets an urgent message from his credit card company telling him he needs to click on a link and update his information or his account will be closed.

Cox News Service illustration (ENLARGE)

A woman sees a pop-up ad claiming it has scanned her computer and found several viruses. She needs to download anti-spyware software immediately or all will be lost.

They make a split-second decision, trust when they should not and become the latest victims of cyberscams, said Ron Teixeira, executive director of the National Cyber Security Alliance. They are not alone.

"People are overconfident when it comes to their security. A lot of people think that they are protected, but the reality is they don't really understand what they need in order to be protected. ... Consumers really need to understand that there are dangers out there," Teixeira said.

According to the Internet Crime Complaint Center, a joint initiative between the FBI and the National White Collar Crime Center, Americans lost $198.4 million to Internet fraud in 2006, an increase of 8 percent from 2005.

The number of scams reaches its highest in the months leading up to Christmas Day, when online shopping is at its highest, Teixeira said. Scammers prey on the fear that gifts will not arrive on time or a problem with an account will keep shoppers from using it when needed.

Online frauds constantly are evolving the ways they steal information, scam people out of their money or just wreak havoc, said Marc Fossi, manager of security response at Symantec Corp., a computer software company. This means Internet users have to be aware of those changes as well.

One of the most common methods cybercrooks use to steal information from people is with phishing e-mails, which involve sending spam or pop-up messages with links to lure personal and financial information from unsuspecting victims. Sometimes the links take people to a spoof site that looks like their bank or credit card company's site, and it asks them to provide certain information.

"You enter that information, and it might actually forward you to the bank's legitimate site at that point. In the meantime, your login information is being collected by the attacker," Fossi said.

Most financial institutions refrain from sending e-mails with links because of these scams, Fossi said. When people get such an e-mail, they should not click on the link. Open a new page to look for the official Web site or phone number of the institution and contact it directly.

To help protect against the viruses some scams carry, people need to have anti-spyware and anti-virus software and a firewall on their computers, Teixeira said. Anti-virus and anti-spyware software protect a computer from viruses that destroy data and spyware that monitors or controls a person's actions. A firewall blocks unauthorized access to a computer.

A survey released by the alliance and McAfee Inc. revealed that 78 percent of consumers do not have the security technologies needed to thwart a cyberattack.

Consumers need those three protections and need to keep them updated, Teixeira said.

"If someone does download a virus, you are relying on your security software to catch that virus. If that virus is too new and it is newer than your last update, your security software is not going to catch it," Teixeira said.

Be wary of fake ads that use scare tactics about viruses or offer unbelievable deals, said Danielle Yates, communications director for the Internet Education Foundation. They could be selling fake products, such as anti-spyware software, or they might lead to Web sites that will download malicious viruses onto a computer.

"A few of the signs are flashy advertising typically in e-mails or in banner pop-up ads like when you do a Google search. They'll be flashy. They will have high-pressure sales, and a lot of times they'll use words like free, which we all know that, more often than not, nothing is ever free," Yates said.

Other scams that people need to be aware of include:

Fake charities – Reputable charities do not solicit by e-mail, Teixeira said. People who want to donate to a charity should find its Web page or go to a site such as give.org, which has background information on different charities.

Online auctions – If a product looks too good to be true at that price, it probably is. Look for sellers with good ratings.

Fake retailers – Look for legitimate phone number and address in case there is a problem with the product. Only buy from sites that use encryption to secure credit card information.