What are the characteristics of an Oligopoly?

It's an industry run by small number of large firms

Firms which sell the same or different products

Has significant barriers to entry

Oligopoly is a market structure with a small number of firms, none of which can keep the others from having significant influence.

Explanation:

The three most important characteristics of oligopoly are:

(1) an industry dominated by a small number of large firms,

(2) firms sell either identical or differentiated products, and

(3) the industry has significant barriers to entry.