A 'niche' market is a small but potentially profitable
market segment wherein custom-made products or services are
offered by a company. It is a small distinguishable segment
that can be uniquely served. Usually a loyalty business
model is used to maintain profitable volume of sales.

niche market is nothing but he act as a leader in small 
segment. no one competitor  he will maintaining a  monopoly 
position in small segment.for ex: "Amutham cool drinks" in  
Tamilnadu

Niche market is the smaller version of 
(Bigger market)mass market.This is a kind of potential 
market.In the niche market what happen company make target 
to the specific class and they market their product for 
them.This type of  market is also known as target market or 
specific market.Like Junior Horlicks only for kids, virtu 
mobile,diet coke( diabetics patients),etc