People who study population trends have developed a special type of bar graph to show how the population of an area is divided by age and gender. It is called a population pyramid. A population pyramid provides a visual layout about the population in a specific location. By analyzing the trends of past and present populations, this instrument can also be used to project future population. Take a look at the two pyramids below.

Interactive exercise. Assistance may be required. Scroll over the parts of the pyramids below to learn more.

Source: Population Pyramids- US and Nigeria, Wordpress.