A downside to the Internet boom of the past two decades has been the growing presence of bigotry and hate online.
The night five police officers were gunned down in Dallas, Texas, an extremist group called the African American Defense League posted this message online: "We must kill white police officers across the country."
One of the group's followers was Micah Johnson, the Dallas gunman.
"People have more access to hate, and people feel more emboldened to project that hate," said Oren Segal, a representative of the Anti-Defamation League's Center on Extremism.
"The Internet actually breaks down some of these normal sort of codes of conduct we have. In some ways we see quite bit of a spike in hate speech because of the Internet."
The Internet can be a community of hate and extremist organizations with web pages looking for followers.
"The most impactful type of activity online by extremists is really on social media, because social media is really a whole different feeling," said Segal. "It's an ability for you to engage with somebody, create a community, feel like you have like-minded people are are interested in you."
Segal said the challenge comes in fighting hate speech without violating people's rights to free speech.
The Simon Wiesenthal Center tracks extremist websites and networks across the U.S., but there were so many, the center stopped counting two years ago when it had identified 30,000.