Persistent cookies are small pieces of data stored on a user's device by a web browser. Unlike session cookies, which are deleted when the browser is closed, persistent cookies remain on the device for a specified duration or until manually deleted. They help websites remember user preferences, login information, and other settings for future visits. These cookies enhance user experience by allowing websites to recognize returning visitors and provide personalized content. However, they can also raise privacy concerns, as they track user behavior over time. Users can manage persistent cookies through their browser settings to control their online privacy.