It happened. The Earth is now supporting seven billion people. But what can one individual, one of seven billion, do to understand how they fit into the broader scope of the planet? How do all these lives compare? What are the larger trends at work?

To understand the answers to these questions, it's easiest to start at the growth rate of the global population: It's currently growing at 1.2 percent annually, according to a report published by the United Nations. The U.N. also says that in many countries, especially in Europe, populations will decline over the next several decades because fertility levels are expected to remain below replacement levels. The report notes that there's particularly rapid growth in a group of 50 countries classified as least developed countries.

The report splits the world into two categories: more developed and less developed regions. According to the data projections, the less developed regions of the world will populate at a significantly higher rate than more developed regions during the next 20 years; meanwhile, the urban population of the world will increase tremendously and the rural population will begin to stagnate and even drop from now until 2030. In essence, while less developed regions are populating, they'll also be urbanizing.

Urbanization can benefit less developed regions for several reasons. Cities allow greater access to social and cultural services such as health institutions, education and much more. Although dense populations can lead to greater pollution and greater strain on the surrounding environment, people are generally healthier and live longer in urban areas.

As we previously reported, people are living longer than ever before. While ageing can be considered a triumph of modern society—the fact that life expectancy is up and continuing to grow—there are vast differences between life expectancy at birth between countries. Japan, which has the highest life expectancy (82 years) is nearly double many African countries, which have life expectancies of 40 years or lower.

The world's urban population is growing at a staggering rate. The urban population of the world hit 3.2 billion in 2005, and it's expected to rise to five billion by 2030. Fifty-one percent of the current population lives in an urban area, according to the United Nations World Urbanization Prospects.

The five largest urban agglomerations—Tokyo, Delhi, Sao Paulo, Mumbai and Mexico City respectively—equate to 118.59 million people, according to a projection from the United Nations released in 2009. That's roughly 1.7 percent of the total population.

The five most populated countries in the world—China, India, U.S., Indonesia and Brazil respectively—make up 3.215 billion people, according to census results published by the World Bank. That's roughly 45 percent of the globe's population.

Data from World Bank