The main purpose of using session management in web applications is to maintain state and manage user interactions during a session, typically after a user logs in. It helps in tracking user activity, preferences, and authorizations within an application. Proper session management enhances security by ensuring that sensitive actions require adequate user authentication. It also improves user experience, as it allows for session persistence across different pages and actions on the website. Effective implementation prevents session hijacking and ensures that user data remains confidential and secure.