Central Depository Services (India) Limited, or CDSL, is one of the two depositories in India, along with NSDL. It began operating in 1999 and holds securities in electronic form on behalf of investors, who access it through a depository participant such as a broker or a bank. When an IPO is allotted, the registrar sends the allotment details to the depositories, and CDSL credits the shares to the demat accounts of successful applicants that are linked to it. It also provides investors with facilities such as statements, an online portal for viewing holdings, and a grievance process. CDSL is itself a listed company, and it is promoted by the BSE together with banks, which gives it a link to the exchange ecosystem. Dematerialised shares replaced paper certificates, which removed the risks of loss, forgery and delayed transfers. For IPO applicants, the main thing to know is that the shares are credited to the demat account named in the application, so the DP ID and client ID must be entered correctly. If shares do not appear, the registrar and your depository participant are the first contacts.
Example: Your demat account is with a broker linked to CDSL. After the basis of allotment is finalised, CDSL receives the credit instruction, and your allotted shares show in your holdings before listing.