All you need to know for the Olympics

Channel 7 has the broadcast rights. It said "over 1 billion minutes will be streamed across the 17-day period, with four modes of viewing: live, full replay, Olympic minis (compressed replays) and short form highlights". The network's coverage is free.

Apart from its main channel, there are a raft of online channels which will stream coverage live plus offer highlights.

But the main events - and talking points - will feature strongly on the main channel, with emphasis on Australian interest. Coverage will depend on who's doing well (or badly) each day.

This Olympics is good news for people who like their normal sleeping hours: Japan is an hour behind Australian Eastern Standard Time so events should be timed just right, unlike Rio in 2016, London in 2012 and Athens in 2004.

Swimming finals are always some of the most watched, and most controversial, events of the Games.

Television giant NBC successfully negotiated to shift the gold-medal races to suit primetime audiences in the United States.

Finals will be between 11.30am and 1.20pm Australian time, with the heats to be at night.

Athletics finals, however, will be during night sessions in Tokyo. The men's 100 metres - the most anticipated athletics event - will be in the 8-10.55pm session on August 1 (day nine).

The opening and closing ceremonies start at 9pm on July 23 and August 8, respectively, but Olympic competition begins on Wednesday, with softball and soccer matches. Australia's softball team kicks off the action against the hosts on Wednesday morning.

There will be 339 gold medals up for grabs across 33 sports and 42 venues around Japan.

Australia was 10^th on the medal tally in 2016, finishing the Games with eight gold, 11 silver and 10 bronze.

It was Australia's worst medal haul since 1992 and sparked widespread debate about the lack of success, reports calculating the cost of the 29 medals was $11.72 million each after four years and $340 million worth of funding to get to Rio.

The Australian Olympic Committee scrapped medal predictions for the Tokyo Games to avoid putting extra pressure on athletes.

Anything less than the 29 medals from Rio would be a disaster. Some prediction websites have projected Australia will win 14 gold and a total of 45 medals.

The pool looms as Australia's best chance of boosting the medal haul. Sprinter Kyle Chalmers will defend his Olympic title, Emoly Seebohm and Cate Campbell are chasing medals at their fourth Olympics, and Ariarne Titmus and Emma McKeon are competing in seven events.

If the swimmers fire early, the pressure on everyone else will be eased.

Ash Barty is going to Tokyo fresh off ending Australia's female drought at Wimbledon, and the world No.1 will be battle Naomi Osaka for gold-medal favouritism.

One of the delights of every Olympics is the emergence of new stars, often in sports which are barely watched in the intervening four years (five in this case).

So predicting who will come to prominence is likely to be unreliable.

Skateboarding may be a hit because it can demand such high skill and daring, and because most of us only know it from walking past the local skatepark.

Australia must have a good chance in the water.

Surfing is in the Olympics so Stephanie Gilmore, who has seven world titles, is one to watch but she is up against the pride of the other big surfing nations, the US and Brazil. Forty surfers will compete, half men and half women.

The Australian men's basketball squad looks strong (though nobody would bet on them beating the United States which won gold in 1992, 1996, 2000, 2008, 2012 and 2016).

But if it's to be done, Utah Jazz sharpshooter Joe Ingles has said he will be there in Australia's colours. Philadelphia 76ers forward Ben Simmons has withdrawn from the team.

But who will provide the "Bradbury moment"? (Ice-skater Steven Bradbury won gold for Australia in the 2002 Winter Olympics after the rest of the field bumped into each other in a last corner pile-up).

By definition, the no-hoper only emerges as a winner as a complete and wonderful surprise.

Another delight of the Olympics is the chance to watch the high skills of obscure sports, known previously mostly to participants (think: synchronised swimming in 1984).

This time, there are five new sports - some are old sports but new to the Olympics.

The International Olympic Committee added them to the Tokyo program in a bid to attract younger audiences and reflect "the trend of urbanisation of sport".

The new arrivals are: skateboarding; karate; climbing; surfing and baseball/softball.

On top of that, there will be new events in sports which have been in previous Olympics.

Nine of these new events feature men and women in the same team. These will be in archery, judo, shooting, mixed doubles in the table tennis, mixed relay in the triathlon, a mixed 100 metres relay in the swimming and a mixed 400 metres relay on the track.

Baseball and softball aren't actually new Olympic sports but they haven't been played there since Beijing in 2008.

In men's baseball, the pitcher pitches overarm, while in women's softball the pitch is underarm. The men's bat is bigger but the ball smaller. The distance between each base is 90 feet (about 30 metres) in baseball but just 60 feet in softball.

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The surfing is from July 25 to August 1 but the four dates of the actual competition will depend on the quality of the surf.

Climbers' shoes are so tight that the toes inside have to curl up. Apparently, this gives a better grip on the climbing wall or rock face.

Another delight of the Olympics is to see big stars from global sports such as tennis alongside unknown players from minor sports: multi-millionaire professionals and amateurs, all wearing the same national colours.

Wimbledon winner Ash Barty was set to lead Australia's 11-member tennis team.

"I think making your first Olympic team, particularly as an Australian, we have such a rich history and the Olympics is something I've always dreamt of and obviously super excited to get out there and represent the green and gold," she said.

The winner of the men's title at Wimbledon Novak Djokovic also plans to be there.

"I booked my flight for Tokyo and will proudly be joining #TeamSerbia for the Olympics," Djokovic tweeted.

"With much pride I'm packing for Tokyo and joining our national team in the fight for the brightest medals at the Olympic arenas.

"For me playing for Serbia was always a special joy and motivation and I will give my best to make us all happy. Let's go."

Outsiders can't go. And Japanese people won't be at the events. With the pandemic out of control in Tokyo, the Japanese government decided that even a sprinkling of local fans wouldn't be allowed.

The Olympic Broadcasting Service which supplies the TV feed to Channel 7 was working to create a semblance of atmosphere with added crowd noise.

There will be some people at the Opening Ceremony on Friday evening. According to Japanese media, about 10,000 diplomats and dignitaries will be there - in a stadium for 68,000 people.

This games will be different - though the sport will still be just as intense as every other Olympics.