In order to avail of depository facilities, an investor has to open a beneficiary account with a depository participant of his choice.This is similar to opening a bank account to use the banking services.
Just as one can hold funds in a bank account and transfer funds across accounts without actually handling cash;one can hold securities in a depository account and transfer securities across depository accounts without actually handling share certificates.
The account holder is called 'beneficial owner' in a depository system and the account is known as 'beneficiary account'. More information on the process of account opening and documents required is available at https://nsdl.co.in/faqs/faq.php.