Ad rates are based on Nielsen ratings. They are determined at least twice a year (four times a year for major markets) during sweeps (also known as "the book"), which occur in November, February, May and July. A traditional television season for broadcasters begins with the new fall line up in September and lasts through the season finales in May.

The bulk of broadcast advertising is sold in the "upfront market" in May, in which advertisers are given a discount for buying advertising on an annual basis. Spots that aren't sold in the upfront are sold throughout the rest of the year in the "scatter market." Increasing competition from cable is causing broadcasters to rethink their decades-old scheduling approach. They are now trying to program new shows, particularly reality programming, during the summer months, which had been previously dominated by "repeats."

The value of advertising is also determined by "dayparts." The day is divided up into various parts, based on the size and type of audience watching television at that time. The most lucrative daypart is primetime, when television draws the largest audience, while "the overnight" is the least desirable. A typical day is broken down as follows:

Early Morning 5 a.m. to 7 a.m.
Morning 7 a.m. to 9 a.m.
Daytime 9 a.m. to 5 p.m.
Early Evening 5 p.m. to 7 p.m.
Early Prime 7 p.m. to 8 p.m.
Primetime 8 p.m. to 11 p.m.
Late Night 11 p.m. to 2 a.m.
Overnight 2 a.m. to 5 a.m.

The sales staff offers local sponsors the opportunity to air commercials or to sponsor segments within local broadcasts. They also negotiate barters, trading airtime for goods, like new cars for photographers or a wardrobe for on-air talent. There are also sales reps at the local level who sell spots to national advertisers.

Following is the basic track for a sales career in broadcast television:

1. Sales Assistant (Median entry-level salary is $20,000)
2. Account Executive (Local or National)
3. Sales Manager
4. General Sales Manager
5. Vice President