Microsoft hides file extensions in Windows by default even though it's a security risk that is commonly abused by phishing emails and malware distributors to trick people into opening malicious files.

View file extensions in File Explorer Never be confused about file types I deal with many different file types on a daily basis, whether they are JPEGs, PNGs, PDFs, or Photoshop files.

To avoid being such an easy target, BleepingComputer points out that you need to change Windows 10 settings to enable the ability to view file extensions by default.