The most common greeting today was "Hello, World!" and it seemed the whole world was watching on television as Live Aid benefit concerts here and in London raised tens of millions of dollars for hunger relief in Africa.

The concert ended here tonight 14 hours after it began with the same song it opened with, the USA for Africa anthem "We Are the World." Sung a cappella by Joan Baez in the morning, the song reappeared as a chorale under the guidance of its author, Lionel Richie, joined by Harry Belafonte, Chrissie Hynde, Baez, Sheena Easton, Dionne Warwick, Melissa Manchester, Kenny Loggins, Patti La Belle, Daryl Hall, a 50-member children's choir and most of the 36 acts that had performed during the day.

On the last chorus, the 100,000 exhausted fans at John F. Kennedy Stadium managed to summon enough reserves for a truly rousing and fitting finale to a day when the medium and the message met on the highest plane. It was the liveliest aid of all.

In a triumph of technology and good will, the greatest entertainment package in rock history, ranging from such legendary figures as Bob Dylan, Mick Jagger, the Who, David Bowie, Tina Turner, Duran Duran and Paul McCartney to relative unknowns like the Hooters, came off on schedule and with neither technical snafus nor displays of ego from any of the participants. For the most part, the artists chose to perform the cream of their pop in a program marked by reunion, emotional comeback and an unprecedented level of cooperation among television, radio and the rock community.

The 100,000 sunburned but festive rock fans at JFK Stadium and 72,000 others at London's Wembley Stadium were but a tiny part of a worldwide television audience of as many as 2 billion.

With AT&T telephone lines jammed by the volume of nationwide pledges -- 22,000 calls were attempted during one 20-minute period after the Beach Boys' set -- one ABC television executive told Agency for International Development Deputy Administrator Jay Morris, personal representative of President Reagan, that the final total raised by Live Aid could exceed $100 million. By show's end, Richie reported that $40 million in pledges had already been made. The government of the small Persian Gulf country of Dubai called in and pledged $1.4 million, and response in other countries hosting telethons was reportedly high. The volume of calls in the United States led to a mailing address (Live Aid Foundation, P.O. Box 7800, San Francisco, Calif. 94120) for contributions being broadcast on both television and radio.

And there was backstage talk among several principal participants about organizing Live Aid programs every year until the year 2000 to provide the long-term program Africa needs to overcome its problems.

"See what USA for Africa and Band Aid have done. Marrying the two and involving this new technology is a very fast but logical evolution," said Morris. "The key is keeping up the public awareness after a happening like this."

It was the day the music lived, the day the stars came out to reap so that others might sow.

"It's not just the greatest show on Earth," said concert organizer and Boomtown Rats lead singer Bob Geldof, "it's the greatest gig in the galaxy."

Darlene Tortorella, 28, drove down from Boston Friday night. "From New Jersey on, you could just tell that every car was headed for this concert. We wouldn't miss it for the world. If fact, we're here for the world."

Music was the subtext of the long day, but conscience was the motif of this rock/television extravaganza that was put together in 10 weeks and beamed live via 12 satellites to at least 90 countries and on a tape-delay basis to 50 more, including the Soviet Union and China.

Bands from Japan, Australia, Austria, Germany, the Netherlands and the Soviet Union also participated via live feeds or taped sets. In Moscow, a studio audience of about 200 clapped and cheered on cue for a performance by Autograph, a band introduced to the global audience by a Soviet announcer as "tops of the pops."

Most of the electronic hopscotching was between London and Philadelphia. Prince Charles and Princess Diana, seated in the royal box with David Bowie and Elton John, opened the Wembley concert (at 7 a.m. EST) waving to the crowd as "God Save the Queen" was played; they were followed quickly by Status Quo performing "Rocking All Over the World."

Two hours later, actor Jack Nicholson introduced Baez to the Philadelphia crowd. "Good morning, children of the '80s," she shouted in greeting. Her presence was an obvious bridge between '60s political consciousness and commitment and the new wave of the '80s.

"This is your Woodstock and it's long overdue," Baez added, kicking off a cappella with "Amazing Grace" and segueing into "We Are the World." And though she urged the crowd to join her in singing the former, they seemed willing only to join in the latter.

"You are the world, you are the children," Baez reminded everyone, and everyone seemed to agree. Live Aid rocked around the clock around the world with the likes of Jagger, Dylan, Turner, Bowie, Madonna and five dozen other top-rank acts.

Near the concert's end, Dylan teamed up for an all-acoustic set with Rolling Stones guitarists Keith Richards and Ron Wood. He sang three early '60s songs, "Blowin' in the Wind," "When the Ship Comes In" and "The Ballad of Hollis Brown," a bitter song about a starving South Dakota farm family. Dylan also made a curious aside, suggesting that some of the funds scheduled for Ethiopia be diverted to pay bank mortgages for American farmers facing foreclosure.

Among the reunions: the Who (in London), the surviving members of Led Zeppelin with Phil Collins on drums and Crosby, Stills, Nash and Young, who last toured together 11 years ago.

Perhaps the most emotional moment in Philadelphia involved native son Teddy Pendergrass, making his first concert appearance since a car crash left him a paraplegic in 1982. Pendergrass joined Nick Ashford and Valerie Simpson on their old hit, "Reach Out (and Touch)," using a special microphone attached to his head to deliver a message that had particular significance to him. As the song's opening melody repeated, Pendergrass had trouble starting, asking the audience to "take a moment and listen to the message in this song . . . reach out and touch somebody's hand . . . make the world a better place if you can." Pendergrass ended the song with tears streaming down his face, as did many in the audience.

The British finale at about 5 p.m. EST did not feature the much-rumored Beatles reunion. Paul McCartney sat down at a piano and sang "Let It Be" with some pretty good help -- David Bowie, Pete Townshend and Bob Geldof. At the end of the song McCartney and Townshend lifted Geldof onto their shoulders to thunderous cheers from the Wembley crowd, and then joined with the other Wembley performers for a musically ragged but emotionally right rendition of "Do They Know It's Christmas (Feed the World)," the song that kicked off the rock-against-hunger movement.

The concert was intended to inspire pledges to telethons in more than 40 countries. The list of countries hosting rockathons included Brazil, Turkey, Hong Kong, Ecuador, El Salvador and New Caledonia.

Despite the abundance of talent on stage, all of it donated, there was only one issue: hunger relief. As one sign in the stadium said, "If it can be done, we'll try. If it must be done, we'd better."

It was a thought that counted, and one that was referred to over and over throughout the course of the day. David Bowie dedicated "Heroes" to his son and "all the children in the world." And said George Thorogood, "It's so nice to be in the city of brotherly love, and that's what we're talking about today."

"Anybody got a piece of paper?" asked Scott Bolger, a 19-year-old construction worker from South Philadelphia. Like thousands of other young men at JFK, Bolger was dressed down to the bone in cutoffs and sandals, but, having been a part of history, he wanted to write down Live Aid's number (1-800-LIVEAID) and pledge a week's pay when he got home.

For those fans who planned on spending up to 15 unshaded hours under an unrelenting sun that provoked temperatures in the high 80s and mind-numbing humidity, JFK Stadium was nonetheless the coolest place to be today. "Totally awesome," said 22-year-old Andy Giller of Monmouth Park, N.J. "I don't even like some of these bands, but today I love 'em all."

Like thousands of others, Giller's spirit was never dampened, though his flesh occasionally was by fire hoses and strategically placed showers. Still, by late afternoon, about 400 fans here had been treated for heat exhaustion by a medical staff of 250. About a dozen people were treated for drug overdoses.

At Wembley, things seemed equally under control, though there was a minor disturbance by a group of youths breaking through a door into the grounds and struggling with police. The Associated Press reported that the only casualty was one constable's trousers, which were ripped off during the scuffle.

If Live Aid was a decidedly more controlled affair than Woodstock -- from the size of the crowd to the flow of music -- there was one similarity: a persistent milling around as fans searched for bathrooms, food, drink, shade and contact.

And like Woodstock, too, it seemed a universe unto itself. Concertgoer Stephen Fallon was paged from the stage to be told that the donor kidney he had long awaited was available in Boston, and a police escort took him to the Philadelphia airport for his flight and transplant surgery.

To those in the stadium, Live Aid was a concert, but to the rest of the world it was, more than anything, a television event of unprecedented scale, an attempt at realizing the global video village.

It was television that controlled the pacing and the production, but it was also television that allowed the $7 million in ticket revenues to grow several times over and provide funds to alleviate the hunger now affecting 130 million persons in Africa.

The Live Aid logo, a guitar neck rising out of the outline of the African continent, was a potent symbol of both the power of rock and the dimensions of the tragedy. And with tens of thousands of T-shirts being sold at $13 each, an increasingly visible one, as well.

In Addis Ababa, Dawit Wolde Georgis, Ethiopia's top relief official, thanked the concert organizers, but said thousands of Ethiopians could still die if there is no long-term development aid.

In London, opposition Labor Party legislator Tom Torney said he would ask Parliament to recommend that organizer Geldof be awarded the Nobel Peace Prize, saying, "Bob Geldof has probably already done more to save the lives of famine-stricken people than anyone in history."

A parade of superstars took turns occupying the huge stage at JFK. At 172 feet wide and 112 feet deep -- twice as large as the Jacksons' Victory Tour stage -- it held 1,500 lights and 120 oversized amplifiers. It took 7 million watts of power and 75 miles of electric cable to produce music that could be heard two miles away, but more importantly, a message that could be heard around the world: feed the hungry before they die.

By utilizing a 60-foot-diameter revolving stage, producer Bill Graham was able to keep the parade of pop stars on the tight track the transcontinental television program demanded. As one band performed, another band, and sometimes two, set up behind a curtain, minimizing time between sets. At noon here, sets started alternating between Philadelphia and London, with the English portions appearing on three large screens.

To the fans in Philadelphia it didn't seem to make much difference whether the stars were live and bright or faded and loud; they cheered along, particularly for Ireland's U2, and provided great harmonic support on Queen's "We Are the Champions."

This was a day of bands across the water, and if the emphasis was on straight-ahead rock 'n' roll, the accents were provided by the rap of Run-DMC, the heavy metal of the reunited Black Sabbath and Judas Priest, the jazz-rock of Santana and Pat Metheny, and the solo grace of Joan Baez.

Despite the potential for major technical foul-ups, the transcontinental switches came off with few noticeable glitches. Those watching at home undoubtedly had a clearer, larger, cooler picture than those sweltering in the sun, but not the sense of sudden community that comes from singing along with 100,000 folks on Crosby, Stills and Nash's "Teach the Children" or the Beach Boys' "Good Vibrations."

The musicians showed uncommon discipline in sticking to the tight schedules. No one went over, though George Thorogood brought on Bo Diddley and Albert Collins as surprise guests, and several segues between London and Philadelphia were as smooth as if the live acts had been videos.

At 8 a.m., Philadephia time, Adam Ant had noted from London that "the whole world is watching." That may have been true for television viewers, but those in JFK Stadium were hard pressed to get any details off the three giant Diamond Vision screens, where groups like Ultravox and Men at Work were coming through loud but not clear. But the fans had one major consolation: they were there. Who wants to brag 20 years from now that they were one of the 2 billion people who saw Live Aid on television?

For stadium fans, there were some disconcerting elements. The early feed from Australia was wildly out of sync and the focus kept changing so quickly -- from Japan to MTV audio to Wembley to public service announcements, and most of these never taken to their end -- that fans could be excused for thinking they'd been sun-addled by mid-morning. At one point a tape of "Turn, Turn, Turn" came on, leading to sudden rumors of a Byrds reunion surprise.

The concert was actually opened by 18-year-old Bernard Watson, who had hitched up from Florida 10 days early and camped out in front of the stadium until he caught rock impresario Bill Graham's ear and earned his shot at rock 'n' roll legend. Unfortunately, Watson was awful in a Bob Dylanish sort of way, but with his tortured lyrics and aching harmonica, and with Dylan closing Live Aid here, Watson provided a nice symmetry.

The crowd here slowly expanded to its capacity between the gates' opening at 7 a.m. and Baez's appearance two hours later. There was none of the pushing and shoving associated with most festival-seating concerts, though ticket holders were searched on entry for alcohol, drugs and weapons.

All day long musicians, technical crews and some of the 2,000 members of the media covering Live Aid filled the Hard Rock Cafe, an instant replica of the rock community's favorite in-club built next to the stage. Even the stars paid their way here. All entrees sold for $10, yet another source for the Live Aid trust fund that was swelled by 17 hours of what the Beach Boys described as good vibrations, but was in reality something more: a shot at longer life for millions of Africans.