What are the signs of identity theft?

We’re a personal finance blog that focuses on financial literacy and the basics of personal finance. We’re writing a piece about how to identify signs that your identity has been stolen. What are the warning signs, and what kinds of actions should a person take once they think their identity has been stolen. Also, what are some steps people can take to prevent identity theft? Requirements: We are looking to hear from experts in identity theft and cybersecurity, as well as any other expert who can speak to this topic.