In the current election system existing in India, NOTA is nothing more than a symbol and it does not have any impact on the election results. How much ever votes are cast in NOTA, even if it gets the majority of votes among all contestants, the contestant who has secured the second maximum number of votes will be announced as the winner of the elections. For example, if NOTA gets 1000 votes and X gets 100 votes and candidate Y gets 50 votes, even though NOTA has maximum, the second maximum, which is X will be declared as the winner of the election.
Some of the other important details on NOTA are as follows. It has been there since long, and was called till 2013 as 49 O, and earlier for using the NOTA option they had to be registering their names in a 17A register placed in the polling booth, and only after that, the election commission included button in EVM, so that the voters in NOTA remained anonymous.
NOTA though does not influence results, it can be a reality check for candidates and political parties to analyze where they went wrong and why people hate them. NOTA helps in preventing malpractices or false voting. Because suppose if you don't like to cast your vote also you can go and cast in NOTA so that no others can wrongly exercise your vote with a fake ID or fake details and fake your vote. So NOTA helps in preventing this election malpractice as well.
