10 Most Game-Changing Developments in the TV Industry

The Nielsen Ratings
Tracking American viewing habits through Nielsen is the industry's main measure of success. Michael Blann/Getty Images

You may have a great show, but is anyone tuned in? Never fear, the Nielsens are here, and they can tell you who's watching, how long they watch and what they're eating. (OK, snacks haven't actually made it into the ratings – yet.) The Nielsen Television Index starting collecting data in 1950. A meter attached to a television tracks what's viewed and sends the info to a computer center. Across the U.S., Nielsen families are selected to match demographic and racial distributions.

These TV ratings were not only used to help determine which series stay on the air, the numbers are also vital to advertising. The better a show's ratings, the more advertisers are willing to spend to get their commercials in front of many, many eyes. But simple numbers aren't enough. Advertisers care about demographics. Got a fancy new car to sell? You don't want to put your commercial in front of a bunch of kids. It's important to hit the intended audience. And make no mistake; those advertising dollars are crucial – and ubiquitous. When you take away commercials and network promos, the average "hour-long" drama is around 40 minutes long [source: Jacob]. Or 40 minutes short.