Mass media is a type of media that reaches the masses (naturally). To become “mass” the media ought to be accessible (affordable) and understandable by the masses. Where in Western civilization Internet is considered “mass media” it is hardly media at all in places where people don’t have access to electricity, not to mention the Internet.
In our civilization, TV, newspapers, the internet, and radio are all considered mass media. They are all connecting a large number of people, and are capable of sharing information in very short periods of time.