JACKSONVILLE, Fla. -

For many people, it's hard to imagine a life without social media sites like Facebook and Instagram.

But some users of those sites have had to after they were locked out of their accounts and told to provide proof of a government-issued ID.

"That's kind of surprising that like a free thing like Facebook would do that," site user Xander Jackson said.

Someone who's not surprised? University of North Florida visiting professor Murat Al.

"It is scary. It is actually more than scary," he said.

Al is an expert in information security and knows a lot more about social networking sites than the average person. But don't go looking for his Facebook account. He doesn't have one, and he says he never will.

"Whatever you share with others, it will be used against you at some time," Al said. "This is what I think."

He said users shouldn't share their government-issued photo ID with Facebook. Al said they should just walk away.

It's what Anneliese Delgado would do.

"I mean, there are other social media things you can use -- Twitter, Pinterest," said Delgado, who uses Facebook. "So I would take my business somewhere else."

Al, however, said keep this in mind: Anytime someone posts anything anywhere on the Internet, he says that information is at risk of being hacked.

"Nobody has the power to safeguard this information, and information breach is not a question of 'if,' it's a question of time. It will happen," Al said.