The full form of DP Charges is Depository Participant Charges. It is applicable when you sell the shares from your Demat account. These charges have a fixed rate irrespective of the number of shares you sell.
DP Charges are levied by a Stock Broker (Depository Participant) & Depository (NSDL & CDSL).
So who is a Depository?
Depositories (NSDL & CSL) are the government bodies that provide Demat services to the stockbrokers. Every Stock Broker is registered with NSDL or CDSL or Both and is called a Depository Participant. All the shares you buy in the stock market are stored safely with the Depositories and not Stock Brokers.