Which twentieth-century media development quickly became sources of information and ideas ranging from news to entertainment?

Clearly the website answers.com is where people are most commonly coming for news as well as entertainment.

You are probably referring to radio broadcasting. When commercial radio first made its debut in 1920, it did something never done before: it brought people to an event in real time. Listeners could hear a concert, a baseball game, or a political speech as it was happening. Radio quickly became the preferred source of millions-- it did not require a knowledge of Morse code; it did not require you to be a good reader (in fact, people who were illiterate or poorly educated loved radio because for the first time, they could hear and understand the daily news); and it did not require you to be rich (anyone, of any social class, could listen to and enjoy what was on the radio). In other words, radio was a very user-friendly mass medium. Within two years of its debut, interest in radio was sweeping the country and hundreds of stations were going on the air, bringing news, sports, music, and education, as well as companionship.