Is your child vulnerable? With over 21 million children under 18 years old online (Pew Internet study, 2005), virtual reality has become a haven for the estimated 50,000 sexual predators crawling the Internet at any given time (NetSafe).

Their goal: To seduce your child for sex. And they've been a busy bunch in their appetite for kids. Total sales of child sexual abuse images for 2004 alone were estimated at $20 billion.

So how do you protect your children from Internet perverts? Can a sexual predator's profile work to your advantage? And what are the warning signs that your child is being preyed upon?

The National Center for Missing & Exploited Children says that child out of five is the victim of an indecent online proposition. And it's likely more. Less than 10 percent of unwanted advances actually get reported to authorities. A major component of this is disconnect in the home.

Seventy percent of unwanted sexual solicitations occur on a child's home computer, according to a Youth Internet Safety Survey. More than 75 percent of these are not reported to the parents.

How is this so?

While 71 percent of parents think their children's Internet surfing is for academic purposes, according to NetAlert, only 23 percent of teens confirm such. They're busy doing other things online.

Almost all unwanted sexual solicitations involving teens take place in a chat room or via instant messaging. The child who makes for easy prey is the one who ...

— Is vulnerable, depressed, feeling isolated, and lonely.

— Feels disconnected from you, the parent.

— Is emotionally or intellectually lagging in maturity.

— Has poor grades.

— Has been the victim of prior sexual abuse.

So who's doing the soliciting? When I think sex predator, I have this stereotype of the creepy looking pizza delivery guy. You know, the dim-witted, greasy-haired, slob with thick glasses and a poor complexion who likely spends most of his off-hours playing video games or watching porn.

Unfortunately, that’s not the case. Almost anybody, male or female, may be a sexual predator.

At a 2005 congressional hearing, an FBI Behavioral Sciences agent testified that sex predators tend to be white men in their 30s and 40s with above average intelligence. A combination of other factors should also raise a red flag, like premature separation from the military or limited dating experiences. Unfortunately, in knowing nothing about these strangers, it is difficult for us to assess these popular profile characteristics. So you need to be proactive in protecting your child.

Train your child to spot trouble. You need to talk about sex predators before your child is approached. You begin this discussion by letting your children know that there are people who will make up lots of things and who want to touch their body and hurt them.

Explain that nobody really "knows" the people they meet online — that everyone is a stranger and that you never give your contact information to anybody. You also want to highlight the tactics sexual predators use in interacting with youth online.

According to Stephen Dean of "Sexual Predators," major warning signs are:

Predators lie about their ages.

Most predators will say that they are in their 30s. This age range makes them less intimidating, because they're not as old as the youngster's parents. Rather, they're closer in age to one of their icons. The predator may also state that he or she is too old to be chatting with a kid, even suggesting that the child should be talking to someone her own age. The age difference will often be justified, however, with the claim that the predator is a school bus driver or teacher, making them "safe."

Predators will "groom" their prey.

In grooming, a predator is friendly and uses flattery and statements of support to gain the child's trust. They will compliment the child's appearance, focusing on specific physical attributes. Many are careful, using a subtle approach, like offering them money and gifts. They are willing to take weeks or months to win over a victim, often grooming several at the same time.

Predators will play on one's self-esteem.

Predators realize that kids feel insecure, self-absorbed, and vain. So they try to build a youth's self-esteem, fighting teen anxieties by giving them a great deal of attention. They also focus on things kids like, taking an interest in hobbies that appeal to kids.

Predators will not post or send their pictures.

And if they do, then their heads are conveniently chopped off. They will, however, ask the child to post pictures of themselves. They may also show pornographic images.

Predators ask inappropriate questions.

They want to know if your child is a virgin. They will ask how far your teen has gone sexually with a partner. They'll ask if your kid has ever seen someone have sex or masturbate in front of a Webcam. More "innocently," they'll ask if your child has a sibling or if there's the off chance your child is really a police officer or working with the police.

Predators will talk about sex.

They boast about sexual techniques and promise to "teach" their victim. Know that their main goal in the first exchanges is to keep the child talking. In doing so, they'll change the subject often, but will continually revisit sex. They'll also focus on oral sex if intercourse is too threatening.

Predators will propose meeting offline.

A predator will first express interest in calling or exchanging text messages instead of public chats. They will then ask if your child's parents are home or when the child will be alone. If things go awry, they will often threaten to "tell on you." A youth needs to be reassured that it is safe for them to tell their parent or a trusted adult that they have been threatened in this way.

Even after outlining all of this to your child, you need to constantly pay attention to his or her online activities and exchanges with others. Look out for situations in which your child:

— Gets suspicious gifts or money.

— Has unexplained phone or credit card charges.

— Displays secretive or changed social behavior.

— Turns the computer monitor off quickly when you approach.

— Takes an excessive number of sick days.

— Gives sudden importance to an unrelated adult.

To further protect your child, keep your computer in an open area of the home, not in your child's bedroom. Instruct children not to post their schedules on the Internet. No one should know their routine. Take issue with your teen having an older boyfriend or girlfriend. Make it unacceptable that they would get involved with an adult.

Exercise a level of control over your child's use of the phone and e-mail. Check printouts of his phone history or her text messages. When it comes to the Internet, realize that kids may have multiple user names and e-mail accounts. Many parents know of only one.

Lastly, maintain open communication with the parents of your child's friends, even if you don't like them. All of you need to work together on monitoring your children's activities and whereabouts.

I know this has an alarmist tone, but this is not an issue to take lightly. Your child is your most treasured gift and you need to do everything you can to protect your child. The intense experience of virtual reality can feel real to a youngster. They can succumb to somebody posing as a friend, but who wants to harm them. While this is a tough issue to talk about, it is by far one of the most important conversations you'll ever have with your child.

In the Know Sex News …

HPV may cause cancer in men. While human papilloma virus (HPV) is known to lead to cervical cancer in women, the sexually transmitted infection may cause cancer of the tongue and tonsils in males. According to a study in the Journal of Clinical Oncology, men who had cancer due to HPV infection responded well to chemotherapy. Almost two-thirds of the nearly 29,000 Americans who contract oral cancer annually are males.

Supreme Court backs PROTECT Act. The U.S. Supreme Court has affirmed that it is constitutional to prosecute a person who claims to have sexually explicit photos of children, but who actually doesn't have any. In upholding the Prosecutorial Remedies and Other Tools to End the Exploitation of Children Today (PROTECT) Act, the court holds that offers to provide or requests to obtain child pornography are not protected by the First Amendment.

Porn tax proposed in California. California Assemblyman Charles Calderon is seeking to impose a 25 percent tax on the production and distribution of adult entertainment, including erotic films and strip clubs. California is currently dealing with a $17 billion budget gap and the porn tax could result in $4 billion in new revenue.

Dr. Yvonne Kristín Fulbright is a sex educator, relationship expert, columnist and founder of Sexuality Source Inc. She is the author of several books including, "Touch Me There! A Hands-On Guide to Your Orgasmic Hot Spots."

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