Yet even though defensive techniques are now available and effective they can be expensive.They can also alienate some of a site's target audience - especially teen users who expect more freedom of expression.'There are companies out there that are doing a very good job, working within the confines of what they have available,' said Brooke Donahue, a supervisory special agent with an FBI team devoted to Internet predators and child pornography.Still, as the Skout case showed, there are several recent trends that have heightened the concerns of child-safety experts: the rise of smartphones, which are harder for parents to monitor; location-oriented services, which are the darling of Net companies seeking more ad revenue from local businesses; and the rapid proliferation in phone and tablet apps, which don't always make clear what data they are using and distributing.
Like most of its peers, Facebook generally avoids discussing its safety practices to discourage scare stories, because it doesn't catch many wrongdoers, and to sidestep privacy concerns.
As a result, many threats are eliminated without human intervention and moderators at the company are notified later.
Sites that operate with such software still should have one professional on safety patrol for every 2,000 users online at the same time, said Sacramento-based Metaverse Mod Squad, a moderating service.
Technology is available for verifying the ages of Web and app users.
One of the providers is Aristotle International Inc, which offers a variety of methods, including having a parent vouch for a child and make a token payment with a credit card to establish the parent's identity.