JSON Web Tokens (JWTs) are compact, self-contained tokens used for securely transmitting information between parties, often employed by authorization providers to authenticate users and determine their access rights in applications. Secure JWT storage is crucial to prevent vulnerabilities, such as cross-site scripting (XSS) and other attacks that can lead to token theft and unauthorized access. Common client-side storage methods include local storage, session storage, cookies, and in-memory storage, each with distinct advantages and drawbacks. Best practices for JWT storage involve encrypting tokens, implementing token expiration and rotation, handling token revocation, and safeguarding against XSS and CSRF attacks. In mobile applications, JWTs can be stored securely using platform-specific secure storage solutions like Android's Keystore and iOS's Keychain. As JWTs evolve to meet new use cases, including those requiring immediate token revocation, it's vital for developers to continuously assess and update their JWT storage strategies to maintain security and scalability.