The bar chart  (example below) is probably the most used type of chart for good reasons. It is one of the simplest to draw and read and can be used to compare frequencies and values from different populations. The bars can be either horizontal or vertical, depending on the amount of text you have (horizontal makes it easier to read the text). To facilitate comparisons of values, it is usually preferable to order the bars by size from smallest to tallest. The exception to this is if there is an inherent order in the variable, like age groups or wealth quintiles. Care should also be taken to ensure that the bars are wider than the gaps between them.

A subtype is the  stacked bar chart  (example below), which is useful for showing segments of a total when there are not too many segments.

Source: World Health Organization (2014). Global status report on alcohol and health 2014 .

Another subtype is the  population pyramid  (example below) which is a combination of two horizontal bar charts, commonly used to show the age and sex structure of the population of a country or region. Population pyramids are particularly useful to understand the age and sex structure of a population and departures from expectations.

The population pyramid is also useful for showing the age and sex structure of deaths in a population. It displays a country’s mortality pattern in one view, as well as revealing divergence from the normal pattern.