Internet-based identity theft can threaten even the most cautious consumer. The risk of having your personal details stolen is ever present, regardless of how carefully you guard your information.

This danger includes the so-called "dark web" - the part of the internet that is intentionally hidden from search engines and is only accessible through the use of a special browser. This online subsection is invisible to most consumers, which means it can be tough to discover whether it contains hackers and fraudsters with access to your personal information.

A number of companies provide dark web monitoring systems, which promise to check these restricted sites for any evidence of ID theft or fraud. A few companies, such as Experian, have even advertised free, one-time scans.

Even excluding the 143 million Americans whose data was compromised in last year's Equifax breach, cases of ID theft have increased in recent years. The Federal Trade Commission's Consumer Sentinel Network received more than 3 million complaints of fraud and other scams in 2016, compared with a little more than 900,000 in 2006. Still, it's tough to know whether or not these services are helpful enough to warrant the cost.

How do dark web scans work?

Essentially, you provide a monitoring service with any details you want checked - such as your bank account numbers, your Social Security number or medical identification details - and it will survey the dark web to see if this information is being shared.

Michael Bruemmer, Experian's vice president of consumer protection, says Experian's service searches more than 600,000 restricted sites and hosting services. While this number doesn't include the entire dark web, Bruemmer says it covers a significant portion.

"Most of the time, if your information is out there, we're going to come back with some sort of information," said Bruemmer.

If your data is found during one of these scans, the system sends you a notification - Experian uses email alerts, for example - about information that is being shared. Then you can take the necessary steps, such as freezing accounts or changing passwords to resolve the problem.

Most services charge a fee. Experian's basic fraud prevention package costs $9.99 per month and its premium package is $19.99 a month, after a free 30-day membership trial.

Do dark web scans help?

Dark web scans may sound like a clever way to thwart fraudsters, but their true effectiveness isn't certain.

Carrie Kerskie, a fraud prevention expert based in Naples, Fla., is skeptical.

"I personally don't see much value in it," she said. "It gives people a false sense of security."

Instead of doing a dark web scan to feel more secure, Kerskie recommends simply assuming your data has been compromised on the dark web no matter what. That way, you can act as carefully as possible to protect your personal information moving forward.

Kerskie, director of Hodges University's Identity Fraud Institute, says just because a search comes back negative doesn't necessarily mean you haven't been a victim of identity theft.

Bruemmer compares fraud prevention to a home security system. A scan is the equivalent of having just the alarms on the windows checked - it won't ensure you're completely secure, but it will make you feel safer.

"No matter what identity theft protection, credit monitoring or dark web scan, there's always the point to be made that you can't have 100 percent coverage of that particular area," he said. "It's not completely comprehensive, but it's something that's easy to do."

Tips to protect your identity

If you don't want to pay for a dark web scan, how else can you ensure your information is being protected? Kerskie offers a few DIY tips for fraud prevention:

• As soon as you know something is wrong, lock or freeze your credit: If you're worried your information might be compromised, Kerskie says this is the best way to prevent someone from opening an account in your name. As opposed to fraud alerts, which only last 90 days at a time and don't completely prevent new accounts from being opened with your details, a full-on freeze allows you to restrict access to your credit score for as long as you choose. Credit locks serve a similar purpose, however they typically cost a monthly fee to maintain. In exchange for the price, a lock can be ended at any time, whereas freezes usually take a few days to undo. .

• Increase your online presence: "I know it sounds crazy, but if you're not online, you have a greater risk of becoming a victim," Kerskie said. While this advice seems counterintuitive, it's actually straightforward. Ensuring you're signed up for an online account with your bank, phone plan and any other service that uses your personal information will prevent fraudsters from opening these accounts with your information.

Never use public Wi-Fi: Kerskie says hackers can easily set up internet login pages that look exactly like the sort of sign-in system you'd use at your favorite coffee shop or restaurant. Once you type your personal details into one of these false networks, it can then be used by fraudsters to steal your information.