A dot plot shows one or more quantitative values per category by plotting one or more dots per category on a numerical (or date-time) axis. A dot plot with only one value per category makes a comparison between those categories very easy. When the dot plot has multiple values per category, you can also compare within the categories. This results in a chart type that packs a lot of information in a small space.
Since the dots communicate information via their position on the axis, and relatively via their position towards each other, the start- and end-point of the axis should be based on the minimum and maximum values in the data. There is no need to start the axis at zero.
By adding a connector between the dots, you can add an extra dimension to an already information-dense chart: The connector adds a focus on the delta between two values or the range between a minimum and maximum value.
A categorical scatter plot is very similar to a dot plot. The only difference can lie in the way the data is handled: In a categorical scatterplot, the data is mostly provided in a flat table, in a dot plot, the data is already pivoted and split into series.
A lollipop chart is like a marriage between a bar chart and a dot plot. It’s closely related to a bar chart since the stick needs to start at zero and the dot is added on top. A lollipop chart is often used to avoid a moiré effect when there are a lot of categories visualized.
A dumbbell chart is a dot plot with two connected values per category. It is great when you want to emphasize the delta between the two values. When you add arrowheads instead of dots, we speak of an arrow chart, when you don’t add marks at all, and just leave the connector, we have a range chart.
A beeswarm chart is like a dot plot with “a lot” of values per category. These values are each represented by one dot, and the swarm of dots represents the distribution found in the data. Instead of packing them in bins, the dots are scattered around each other.
The most simple alternative to a dot plot is a bar chart. Instead of using relative position on the numerical axis, the bar chart uses the length of the bar to communicate the value. To replace multi-series dot plots, one can choose between a stacked or a grouped bar chart. This makes comparison within and between categories possible.
A slope chart is a perfect alternative for a dumbbell chart. It emphasizes the evolution between two values by using the angle of the slope to communicate the difference.
A range chart can be used as an alternative for a two- or multi-series dot plot if it is more important to focus on the delta between two points or the range between the minimum and maximum value of multiple points.
A dot plot can be a pretty simple chart. Its minimum pack is categorical and numerical dimensions and a fixed size mark. Color is the thing that adds the edge to this chart. It might be used to place simple accents, but it can also add a new dimension: numerical, categorical, or even time.