BOID stands for Beneficial Owner Identification Number, which is a 16-digit number consisting of 8 digits of DP ID and 8 digits of Client ID. It is used to identify a unique demat account held with the depository (CDSL) through your Depository Participant (DP). When a new account is activated in the CDSL system with a valid email ID, a log-in for "easi" will be created for the BOID automatically. The BOID is also known as the Demat account number or BO ID. It is important to note that the DP ID is a number allocated by the CDSL and NSDL to your depository participant, such as a brokerage firm or other financial institutions such as a bank. The first 8 digits of the Demat account number represent the DP ID and the last 8 digits make the BO ID.