The dark web is a rogue part of the world wide web that you cannot access through traditional search engines and browsers. Among other things, the dark web is traditionally used for illegitimate trade of stolen personal information and is often how an identity thief would get access to your information.
Activate Software Privacy Suite searches the Dark-Web for traces of your email account or password in breached databases that were exposed in the dark web.
Note: There is no way for any company to search the entire dark web. A scan can uncover if your login credentials have been exposed in known breaches of sorts, but it is not a guaranteed detection method.
If your email address or password have been located in data breaches, change your passwords to strong/secure passwords that you have not used in the past.