In his internet safety presentations at schools, Justin Gaertner emphasizes that safety "comes back to parents and kids being vigilant."

"If you see something, say something," he tells his audiences.

Wounded in war while serving in Afghanistan as a Marine veteran, Gaertner works with the Department of Homeland Security, pursuing predators who collect and trade child pornography -- more accurately termed, child sexual abuse imagery -- on the internet.

"We all have to be very careful," Gaertner told Catholic News Service.

One resource for guidance on internet safety is the National Center for Missing and Exploited Children, or NCMEC, runs the website with tip sheets and guidance tailored for various audiences. The site is one of more than a dozen sites with child safety resources the U.S. Conference of Catholic Bishops' Secretariat for Child and Youth Protection lists.

For parents, NCMEC suggests the best way to protect your children is to actually engage with them in accessing things online: offer to play the games they like, ask them to show you what platforms they use, discuss being respectful online and never responding to sexual questions or requests for pictures.

"Your kids might not tell you everything but ask anyway," the center says. "Regular conversations about safety can go a long way in increasing trust and communication."

The site tells parents: "No technology, no piece of software, no parental control is ever a substitute for active and involved parenting. The most effecting internet safety tool is you!"

Launched in 2013 by the USCCB's Department of Communications and the Greek Orthodox Archdiocese of America, the Faith and Safety website has a variety of resources, including reviews of mobile apps; ways to address issues faced by children online, such as bullying; and resources to educate parents on protecting their home networks.

It also features regular columns by leading Catholic and Orthodox figures on connecting faith and technology, as well as news updates, how-to guides and video content.

"All safety -- especially mobile and online safety -- begins at home," the site's homepage says. "The habits you exhibit about technology use in your home will be the same habits your children learn. ... Model the behavior you yourself expect from your children."