JWTs are compact, URL-safe tokens that contain a set of claims and are used for authentication and authorization purposes. Storing them securely is crucial to prevent attackers from gaining access to sensitive data. The best practices for storing JWTs securely include using secure transport, short-lived access tokens, rotating refresh tokens, using secure cookies, preventing XSS attacks, implementing token expiration and revocation, considering in-memory storage for sensitive data, and protecting against CSRF attacks. Always serve your application over HTTPS and ensure that sensitive data is encrypted in transit. Implementing a Content Security Policy (CSP) can also help restrict the execution of unauthorized scripts. By following these best practices, you can keep your JWTs secure and ensure that your application remains safe from common attacks.