Explain the role of IDRs, ADRs …

Global Depository Receipts (GDR) are the depository receipts denominated in US dollars issued by depository bank to which the local currency shares of a company are delivered. GDR is a negotiable instrument and can be traded freely like any other security. In the Indian context, a GDR is an instrument issued abroad by an Indian company to raise funds in some foreign currency and is listed and traded on a foreign stock exchange.

American Depository Receipts (ADR) The depository receipts issued by a company in the USA are known as American Depository Receipts. ADRs are bought and sold in American markets like regular stocks. ADR is similar to a GDR except that it can be issued only to American citizens and can be listed and traded on a stock exchange of USA.

Indian Depository Receipt- IDR is a financial instrument. It is issued  by domestic depository to the Indian citizens against the shares of foreign company. IDR is denominated in Indian rupees. It helps issuing company, i.e. foreign companies to raise capital from Indian securities market.