A demat account holds securities electronically, like stocks and mutual funds. Adding a nominee ensures smooth transfer of assets after the account holder’s demise. Online, visit NSDL, authenticate using DP ID, Client ID, PAN, and OTP, nominate, enter details, verify with OTP, and complete Aadhaar e-Sign. Offline, request a form from your DP, fill accurately, provide ID proofs, and submit. Follow the process carefully for successful nomination.