How do I read the ratings?

A Nielson rating may look like this:

8pm - NBC - TVgasm The TV Show - 10.0/18

Focus on the 10.0/18. The RATING, 10.0, on the left represents the actual number of households that watched a show. One rating point equals 1,102,000 households. The SHARE, 18, on the right represents the show's proportion of the total households watching television at that time. For example, TVgasms TV Show has a 10 rating/18 share. That means 11,020,000 households are tuned in to the show and 18% of all the households with a TV turned on are watching that show. Ratings and Share are customarily broken down for various DEMOs -- a demographic grouping of viewers, like 18-49 adults or 2-12 children or 18-34 women, etc. Advertisers, and therefore networks, covet the 18-49 adult demo, and so tend to concentrate on that number.

After the jump, find last nights (18 - 49 year old) Nielson Ratings on major networks during prime time.