Oligopoly is a market structure with a few firms collectively control a industry and, none of which can shield the others from having noteworthy impact.
A monopoly is one firm controlling an industry, duopoly is two firms controlling an industry and oligopoly is two or more firms controlling an industry .
There is no exact limit to the number of firms in an oligopoly, yet the number must be low enough that the activities of one firm altogether impact the others.
Oil companies, airways, and Telecommunication service providers are some examples of oligopolies.
The economic and legal concern is that an oligopoly can square new participants, slow development, and inflation, all of which hurt consumers.
Firms in an oligopoly determine prices, whether collectively or by forminga cartel or under the guidance of one firm, rather than taking prices from the market. Net revenues are in this way higher than they would be in a more competitive market.
Telecommunication Networks in India are a perfect example for an oligopoly. When Jio changed its voice and internet plans and introduce price cuts, the other networks like airtel, vodafone, idea and BSNL had to follow. Jio as one firm was able impact the other firms by introducing serious price cuts.