There are more than 8 billion people, and counting, spread out across Earth.
It's a number so enormous, it can be hard to fathom unless you break it down into a more comprehensible scale.
More than a third of the world's population live in the neighbouring countries of China and India.
By way of comparison, this is what Australia looks like next to these population powerhouses.
Since records began in the 50s, China has held the title of the world's most populous country.
But its population is in decline and, this April, according to UN population projections, India will overtake it.
India is expected to continue to widen the gap until its population peaks in 2064.
To understand these seismic shifts, it helps to look at the make-up of the two countries and how they have changed over time.
Not only is China's population growth stalling, it is also ageing.
The median age there is now 39. In India, it's 28.
More than 40 per cent of India's population is under the age of 25.
It's both an exciting and daunting prospect for India.
On the one hand, its young population provides a huge potential workforce.
A demographic dividend that, if harnessed, could see India become one of the most powerful nations on the globe.
But that means India needs to provide jobs for all those young people. If it can't, there is a risk they fall further into poverty.
And in a bid to control the boom, there are concerns India may make the same mistakes as China, or revisit a dark chapter in its past.
What's behind India's population boom?
There are three factors that help populations grow: birth rates, life expectancy and immigration.
For India and China, the key ingredient is the number of babies born each year.
In both countries, this number is falling — women are having fewer babies than they were in previous decades.
It's just that India's fertility rate is dropping slower than China's.
Taking a closer look at where Indian babies are still being born reveals an interesting pattern.
The population boom has been driven by two northern states of Bihar and Uttar Pradesh, where people are having more babies than in the southern and western areas, which are wealthier and more educated.
Demographers say the proliferation of family planning and contraception in these southern states is the main reason for dropping fertility rates.
Across India, about a third of married women of child-bearing age don't use any contraception at all.
Among the majority who do, the predominant method is permanent — 60 per cent of those actively trying to prevent pregnancy have opted for a surgical procedure.
"Nowhere in the world do you have such high sterilisation rates," says Poonam Muttreja, executive director of the Population Foundation of India.
"Close to 70 per cent of the women who go through sterilisation have never experienced a temporary contraceptive method."
All sterilisation surgeries are considered similarly effective at preventing pregnancy, but the operations for female reproductive organs are more complex.
Vasectomies, which cut the tube that carries sperm from the testes to the penis, are generally carried out under local anaesthetic. Patients are usually allowed to go home straight afterwards.
Tubal ligations, where fallopian tubes are sealed to prevent an egg from reaching the uterus, and hysterectomies, where the entire uterus is removed, require general anaesthesia. Recovery time can vary depending on the procedure.
So why are so many women choosing sterilisation surgeries?
Many are encouraged by regional health workers employed by the Indian government and enticed by cash incentives.
As the morning fog billows through the air, workers in maroon uniforms knock on every door in the village of Mandura, north of Delhi.
These women are Accredited Social Health Activists (ASHAs), employed by the national government to visit regional areas and educate locals about their reproductive choices.
They know most of the women and children in the village, shouting their names to draw them out of their homes to discuss their health care.
"We go to every home, we meet women, their husbands and their families, we motivate them to opt for permanent sterilisation," health worker Pinky says.
"We tell them one or two children is enough and it's very difficult to raise more children because of cost-of-living rises."
Komal, a mother of two children in nearby Sonipat, says she was initially hesitant about the idea of surgical sterilisation, but eventually took the advice of health workers.
"The health department took my bank account number and told me that 1,400 rupees ($25) would be transferred to me," she says.
"I told the health worker that I want to opt for the operation, she supported me and took me to hospital for sterilisation."
Just five days after Komal had her operation, the health worker who convinced her to get the surgery, Monika, visited to make sure she was recovering well.
Indian women who receive compensation for their sterilisation are less likely to feel regret about the decision than those who are not compensated, according to a 2022 study.
But researchers warn that incentive-driven family planning, which often targets poorer communities, is not as safe or effective as education-based models.
And there are concerns that the offer of cash and appliances may coerce people into having unnecessary and invasive procedures.
"Sterilisation can only get you that far. It is not the only method, and it is not the best method," Jaydeep Biswas, from the UN Population Fund, says.
"We believe that it's the choice that women should have on what method suits her.
"There is a lot of evidence that reversible methods are what young people prefer."
It's not only those who choose the surgeries who stand to benefit under this government scheme. Health workers who refer them also receive a financial bonus.
And as the cost of living rises, bonuses have become a lifeline.
Thousands of ASHA workers have been marching across the country, calling for better working conditions and an increased minimum wage of at least 26,000 rupees ($461) per month.
"The government is giving us just 4,000 rupees ($71) per month," Monika says.
"How can we manage our livelihood on this pay?"
In Haryana, where Komal lives, ASHA workers receive 1,000 rupees ($18) for each woman with fewer than three children who gets the surgery.
For women with more than three children, the health worker commission drops to 200 rupees ($3.60).
"We get incentives for getting people to do reproductive surgery, we benefit and so does the woman," Monika says.
"We've been trying hard from our side and after the birth of their first child, we advise families to maintain a gap between their next one."
Demographers worry that government incentives for health workers are encouraging them to push women into surgery over other, much safer contraceptive options.
"They do not invest in counselling or motivating or sharing more information on the benefits women could experience from temporary methods, especially now that the world has so many long-lasting contraceptive methods," Ms Muttreja says.
"We spend a huge part of our budget on incentives … going forward we should spend that money on introducing and procuring long-lasting methods."
For many Indian women, sterilisation seems like the only option.
Asha has four children and doesn't want any more, but her husband isn't willing to get a vasectomy and she's struggled with other forms of contraception.
"The men in my family say the operation isn't good and there'll be a problem … my husband is very skinny and feeble, so he can't get the operation either," she says.
"We don't want more children because of the high cost of living.
"I want to get this operation so my children can have a better future and we can afford to pay for things."
The ABC has contacted India's health and family welfare ministry for comment on the effectiveness of incentives for surgical sterilisation, but after several requests did not receive a response.
While the Indian government says its family planning program is "target-free and voluntary", experts like Ms Muttreja say India needs men to be more involved and more engaged in contraception.
"It's safer to do male sterilisation, men need to step up," she says.
The national government has suggested it wants to shift the focus towards male sterilisation, but there hasn't been any action so far.
And India's history of population control goes a long way towards explaining why politicians are worried about targeting men.
A history of control and forced sterilisation
For more than 50 years, Govind Lal Taneja has been working at a small tailoring shop on a busy street in Sonipat just outside Delhi.
When he got the job in the late 1960s, Indira Gandhi had just become prime minister.
Gandhi gained almost total control over the Indian parliament and was hugely popular especially among marginalised groups — women, poor and lower-caste people — for her socialist and secularist policies.
Under then-president Lyndon B Johnson, major American corporations such as the Rockefeller Foundation were lobbying for population control, warning too many people would lead to "a world of chaos, riots and war and a perfect breeding ground for communism".
Johnson pressured Gandhi to combat India's growing population in 1966 during her visit to Washington DC.
During the visit, an adviser asked the president if he would like to commit to sending more food aid to India.
"Are you out of your f***ing mind? … I'm not going to piss away foreign aid in nations where they refuse to deal with their own population problems," Johnson responded.
Powerful bodies including the United Nations, the World Bank and USAID were also pressuring the Indian government to introduce sterilisation policies.
In 1975, Indira Gandhi imposed a nationwide emergency.
The following year, as Gandhi's political grasp loosened and protests swept the country, her son Sanjay rose through the ranks to become her adviser.
In response to the pressure around India's population growth, he introduced a widespread compulsory sterilisation program targeting men.
Villages were cordoned off, mainly in poor or Muslim areas, and police reportedly dragged men from the streets to take them away for surgery.
"They took me forcefully, there was a deputy superintendent of police who beat me and took me to the local hospital by force," Govind, the tailor, recalls.
"I told the officials that my wife had already been sterilised, so how could they sterilise me?"
Some men were offered incentives like plots of land, or threatened with fines or job losses if they didn't follow through.
In 1976 alone, an estimated 6.2 million men like Govind were given vasectomies. Most of them were forced into the procedure.
Gandhi's party was voted out of power the following year, after her opposition used the widespread backlash against the emergency and the sterilisation policy to gain support.
India was the first country in the world to introduce family planning and population control methods, but the forced sterilisation scheme is now seen as a dark legacy of Indira Gandhi's government.
Decades on, Govind is calling for the current government to compensate him and others who were brutally coerced into having the procedure.
"The motive behind forced sterilisation was not reducing the population," he says.
"The population could have been controlled if they got people's confidence by consulting them, not forcing them to get sterilised."
Just as communist China's one-child policy has done since its introduction in 1980, India's forced sterilisation policy has haunted future governments, shifting the focus away from men.
"It was a huge setback, even though our planners recognise the need for family planning, it became politically inconvenient," Ms Muttreja says.
"There was a fear of talking about family planning or focusing on contraception, because … the government in part lost elections because of forced family planning.
"In a democracy, you cannot coerce people to accept a method, or accept family planning at all.
"We should have had greater trust in people given the secular decline in families and the number of children people were having."
Despite those political fears, over the years governments have discreetly introduced population control policies, including incentive-based sterilisation programs.
These policies have been described as similarly coercive, and the government has been accused of using them to control the religious make-up of the country.
India's Muslim population has the highest fertility rate among religious groups, followed by the Hindu majority, but Muslims are also seeing the fastest decline in births.
The national government allows the states to adopt their own family planning policies.
Many states led by various political parties have implemented two-child policies that restrict people from applying for government jobs or standing in local elections if they have more children.
Politicians from Narendra Modi's Bharatiya Janata Party, known as the BJP, have frequently blamed population growth on the Muslim minority.
In India's north-eastern state of Assam, Chief Minister Himanta Biswa Sarmam announced a two-child policy claiming that population control was the only way to "eradicate poverty and illiteracy" among Muslim people.
Critics say this is an example of the Hindu nationalist government using population growth as an excuse to target the Muslim minority.
How the changing shape of India's population could determine its future
India's population is on track to reach 1.6 billion in the next 20 years, peaking at almost 1.7 billion in 2064.
But it will have to play its cards right if it wants to become the next global superpower.
An estimated 8 million young people come into the job market each year.
But less than half of Indian adults are employed, compared with two-thirds in China.
Economists say this is the key piece of the puzzle that governments need to address to future-proof India's population and secure a spot in the world's top three economies.
In the country's most densely populated centres, competition on the job market is fierce.
Sohan is part of the 90 per cent of India's workforce in insecure work — without regular pay, stable hours or benefits.
Since he finished university, he's gone from job to job earning, at most, the equivalent of $10 an hour, which he says doesn't cover food and rent.
He's been applying for government jobs, but because of the growing number of applicants as the population increases, he has had no success.
Sohan and his fellow applicants are staging protests in New Delhi, calling for more government job opportunities.
"We have seen in the last few decades that India is facing a problem of unemployment and we haven't been able to give sufficient jobs to our young people," he says.
"It’s becoming harder day by day … if one vacancy came out of the gate, then there are thousands of applications for the same job.
"I've been thinking about travelling overseas … to some country like Australia, where we can get a good salary."
Sohan's experience is not unique.
Last year, more than 10 million people applied for 35,000 jobs with one of India's largest employers, the railways.
In the states of Bihar and Telangana, applicants were so frustrated by the "non-transparent" hiring process that protests spiralled into violence.
Students were accused of stopping trains and setting fire to coaches.
As its young people fight for jobs, perhaps India's biggest untapped asset is its women.
Only 10 per cent of adult women have a job in India, compared with 69 per cent in China.
To solve this, India not only needs to create more jobs for women, but also ensure they have enough facilities to feel safe travelling to and at work, as well as flexible conditions like maternity and period leave.
"Ultimately, as a society moves forward, the development of women and children are real markers of advanced society," the UN Population Fund's Jaydeep Biswas says.
India's population statistics aren't just numbers.
They are determining almost every aspect of life; from jobs, to welfare and healthcare policies, education and the family unit.
Researchers focusing on this crucial space agree that while India has some difficult problems it needs to overcome, the country can become the next superpower, in a sustainable way.
"It's a once-in-a-lifetime opportunity for India, as India's young people take charge, and they are more skilled, and they are more digitally enabled," Mr Biwas says.
"It's a great moment. We think India is at a great juncture, the direction is absolutely right. India's positives are far outweighing the constraints."
For Komal, recovering from her sterilisation surgery in bed while her two children run around the family home, this future begins now.
As her kids grow up over the next few decades, the decisions of India's government today will determine whether they're employed in a developed, thriving country, or one that's struggled to create a comfortable life for its people.
"My children's future will be good … we will always hope for the best."
Credits
Reporting: Avani Dias and Som Patidar
Photography: Som Patidar
Design: Alex Palmer
Development: Katia Shatoba and Thomas Brettell
Digital production and graphics: Lucy Sweeney and Mark Doman
Additional photos and video: LBJ Presidential Museum, Visnews via ABC Archives, Associated Press
Notes about the data used in this story:
The data used in the introduction to this article uses was sourced from the UN's World Population Prospects. In all the visualisations forecasting population make-up and growth, we have used the UN's "medium scenario projection".
India’s National Familiy and Health Survey is run by the country's Ministry of Health and Family Welfare. You can read for about how the data is collected here.
