What is the difference between self, internal and external indicators?

Indicator is a substance which changes the color in response to a chemical reaction(specially in titrations).

There are three types of indicators which is discussed below:-

Self Indicator:- Basically these are not an indicator it is one of the reacting species of titration which is after completion of reaction changes the color of the solution itself.
Internal Indicator:- These are those indicators which takes part in the reaction(titration) and after completion of titration it changes the color of the solution indicating the sharp end point.
External Indicators:- Indicator which never takes part in the original chemical reaction but after completion of reaction it also changes the color of solution to indicate the endpoint. External indicators is not recommended as it leads to loss of some volume of the reaction mixture.