The most notorious form of Online Scam is where the online fraudster sends out phishing (the practice of sending fraudulent emails that would induce the reader to divulge sensitive or personal data) emails.
The content of these mails read similar to the routine mails that may come from your bank, or a website that you usually visit. For example, an online shopping store, a promotional email from the bank you have an account, or a cloud storage company offering you a huge discount on data storage.