CINCINNATI - Goodbye,

Guiding Light

. Hello, YouTube.

Procter & Gamble Co., the maker of household products, whose sponsorship and production of daytime TV dramas helped coin the term soap operas, has pulled the plug after 77 years. Instead, the manufacturer of Tide detergent, Ivory soap, and Olay skin care is following its customers online with a big push on YouTube, Twitter, and Facebook.

"The digital media has pretty much exploded," Procter & Gamble marketing chief Marc Pritchard said in an interview. "It's become very integrated with how we operate. It's become part of the way we do marketing."

The last P&G-produced soap opera, As the World Turns, went off the air in September. The show was the leading daytime soap for decades, but, at the end, had lost about two-thirds of its audience. Now, P&G has decided not to produce any more soap operas.

Over the years, P&G produced 20 soap operas for radio and TV. But ratings for daytime dramas have been sinking for years, as women, their target audience, increasingly moved into the workplace, switched to talk and reality shows, and spent more time using online media and social-networking sites.

P&G, the world's biggest advertiser, still buys individual commercials on daytime dramas. But the dollar amount has shrunk. P&G will not say by how much.

Dori Molitor, whose WomanWise L.L.C. agency specializes in marketing brands to women, says big companies are realizing that social media are an efficient way to connect with customers.

"Social media has become mass media, and for women especially," she said. "I think for all marketers, these one-way, 30-second [TV] spots are very expensive and are less effective for the way that women make decisions."

Marketing experts say that the biggest companies were generally slow to adapt to the rapid rise of social networks, but that beverage rivals Coca-Cola Co. and PepsiCo Inc., and P&G and fellow consumer-products-makers Unilever and Johnson & Johnson are among those quickly making up for lost time.

In recent months, P&G began selling Pampers diapers on Facebook, offering an iPhone application for Always feminine products that allows women to track menstrual cycles and ask experts questions, and using social media to turn a campaign for the venerable Old Spice brand into a pop-culture icon.

The "Smell like a Man, Man" commercials starring hunky former football player Isaiah Mustafa became a YouTube sensation, drawing tens of millions of views. They also spawned parodies such as one with Grover of Sesame Street, and generated another round of attention with Twitter questions that Mustafa answered in videos - such as on ABC's Good Morning America, when he suggested that President Obama could improve his standing with female voters by wearing only a towel and beginning speeches with "Hello, Ladies!"

That gives P&G a bigger bang for its nearly nine billion bucks a year spent on advertising.

"It is such an effective advertising campaign that we are getting impressions that we did not pay for," chief executive officer Bob McDonald told investors recently, recounting that he saw an editorial cartoon showing Obama on horseback, a takeoff on Mustafa's "I'm on a horse" Old Spice catchphrase.