Child mortality – one of the most important aspects of development – has always been a focus for us. But in our new Our World in Data series we want to go further than this: exploring in detail the differences in child mortality across the world; what children are dying from; and what we can really do about it.

How does sex ratio at birth vary across the world? We might expect that naturally an equal number of boys and girls are born, but this is not the case. There are biological reasons why more boys than girls are born each year: around 105 boys per 100 girls. But in countries with a strong son preference, the sex ratio is even more skewed.

Vaccines have provided some of the greatest interventions to global health to date. But attitudes to vaccination – whether they are safe, effective and important – are often divisive. Here we look at results from the largest global survey to date – the Wellcome Global Monitor – on attitudes to vaccination across the world. 92% of the world thinks vaccines are important for children to have, but in some countries skepticism on their safety is as high as 1-in-3.

92% of people in the world think vaccines are important for children to have. But in some countries, skepticism about their safety is as high – in some cases every 3rd person. What effect do public attitudes have on vaccine coverage rates, and what can we do about skepticism to vaccines?

Are we happier when we spend more time with others? Studies suggest social relations are key factor in happiness & life satisfaction. We take a closer look at the evidence for how much social connections matter for happiness.

Loneliness has been reported to be as lethal as ’15 cigarettes a day’. What is the evidence for this? We take a deeper look at the data and research on the link between loneliness and health and wellbeing.

The UN projects that the world population will increase from 7.7 billion today to 10.9 billion by 2100. Most of this growth will come from Africa; its share of the world population will rise from 17% to 40%. More than 8-in-10 people will live in Asia or Africa by the end of the century.

Many lecturers and teachers use Our World in Data in their teaching. This spans a range of levels from primary school to post-graduate university education. Matthew Cone, a US high-school teacher shares how he uses OWID with his pupils.

Our World in Data gets lots of feedback on how our work is used by policymakers, journalists, researchers and the public. But sometimes we get feedback from people who us in ways we could never have imagined. Dr Jill Gordon shares her experiences on how she uses OWID in her work as a medical doctor.

South Koreans are on average 32-times richer than in 1950; Romanians 20-times; Chinese 16-times. Other countries stagnated and remained poor. We look at how incomes have changed around the world and why it matters.

There is a cross-country correlation between democracy (elections, freedom of expression, equality before law etc.) and population health. We take a look at these correlations and whether there is good evidence to suggest causality.

Global population has increased rapidly – particularly over the past 100 years. But this growth is temporary: we take a look at population growth over the past few centuries and what we can expect for the future, drawing on the latest UN Population Prospect projections. It maps the transition from rapid growth to a new equilibrium.

In our long history, how likely was it that our ancestors died as children? Historical studies suggest that around one-quarter of infants died in their first year of life and around half of all children died before they reached the end of puberty. It’s only in the very recent past that we’ve seen dramatic improvements.

There is a large disconnect between what gets covered in the media and the day-to-day reality for most. How do causes of death in the US match with media coverage and what people search for online?

50 years ago the average woman in world had five children. Since then, this figure has more than halved. Yet the global population is still rising – why is this the case?

5.4 million children under 5 die every year – that’s 15,000 every day. Yet this is an everyday tragedy that never makes the headlines.

The human population has been a young one for most of its history: high fertility rates and short lifespans mean children have accounted for a large share of the population. But the world is ageing: there are now more people older than 64 than younger than 5 years old. This marks a historic demographic change.

The world has committed to ending extreme poverty by 2030. But projections suggest we’re far off track: although global extreme poverty is expected to continue to fall, an estimated 500 million will still live in extreme poverty in 2030.

How hard is it for women to make it to the top? Recent research using income tax data from a number of high-income countries casts light on this. Although improving, we see that women are still very under-represented at the top of the income distribution.

Where do we find life on earth? Despite being vast, the oceans are home to just 1% of life – but the majority of animals. See how the different lifeforms are split across these global environments.