Cookies vs. LocalStorage: Storing Session Data and Beyond

Cookies and LocalStorage are two popular methods for storing data in web browsers, each with distinct uses and limitations. Cookies, introduced in the mid-1990s, are small data blocks sent with every HTTP request, making them ideal for session management and authentication, especially when security is enhanced with HttpOnly and Secure flags. On the other hand, LocalStorage, part of the HTML5 specification, allows web applications to store larger amounts of data (5-10MB per domain) client-side, persisting beyond browser sessions without being sent to the server, making it suitable for non-sensitive client-side data like user preferences or UI states. While cookies are advantageous for secure, server-side session management and cross-domain data sharing, LocalStorage is better for persistent client-side application data, particularly in Single-Page Applications (SPAs). However, LocalStorage is vulnerable to XSS attacks and is generally not recommended for storing sensitive information such as session tokens.