Central Depository System or C.D.S
Its computerized ledger systems which enable the transfer or holding of securities with no necessitate for physical movement. The shares or ownership of security is by the use of a book entry instead of physical exchange CDS is for security what such a bank is for cash transfer among banks. As like A and B are 2 shareholders of XYZ Ltd. XYZ Ltd. does not necessitate delivering the share certificate to A or B however a ledger account for both shareholders would be maintained at the CDS. Their accounts will be credited along with the number of shares. Whether A want to sell shares to B the CDS will debit A's account and credit B's account.