Ransomware is the new form of a computer virus. It affects mobile phones mostly. You’re browsing the web and click on a photo hosted on a fishy website. It downloads a virus that locks out your phone and encrypts the data stored. You get a message saying that they promise to send you the password to encrypt it if you send money to a certain account.
Being anonymous online might encourage you to write something you’d otherwise wouldn’t say to somebody’s face. The thing is, the anonymity is often an illusion, and if you happen to get a stalker or piss off the wrong person, they can make your life miserable. Especially if your username matches your Facebook /other accounts. Often a mere google search of your username may lead to your other accounts, with additional information. There’s even websites that offer bots that put together a profile of a person online, searching for more and more data based on the info you provide them.