What is a depository

What is a depository and what services they offer to the investors?

Depository is an institution or organisation, which holds securities (e.g. shares, debentures, bonds, etc) in electronic form, in which trading is done.
Depositories provide following services:
(i) Maintain records of shareholding in electronic form.
(ii) Enable deposit and withdrawal of securities to and from the depository through the process of dematerialisation and rematerialisation.
(iii) Effect the transfer of securities traded in the depository mode on a stock exchange.