Star series notes, in its simplest definition, are replacement 
notes for errors in printing.
You may be aware that banknote production is a one complicated process which involves several steps. Let’s try to understand it with the example of a Rs 100 note. They are usually issued in bundles of Rs 100 notes and each note is placed in a sequential serial order. During the process of production, especially during numbering, there could be errors that disturb the continuity of the series. These notes are then replaced. This is where notes of the star series are used.
Star series notes are inserted, replacing defective notes in a bundle that is arranged in a particular sequential order.
They are printed with a star symbol in the numbering panel. For example 9AA*034801. There is a prefix of three characters before the symbol, as well as a six-digit serial number that follows. The series was introduced by the Reserve Bank in 2006.