A scatter diagram is a graphical representation of data points in a two-dimensional space. It displays the values of two variables, with one variable plotted along the horizontal (x) axis and the other along the vertical (y) axis. Each data point is represented by a dot, allowing us to observe patterns, trends, and correlations between the variables.

A frequency diagram, or histogram, is a graphical representation of data that groups data points into intervals (or bins) along the horizontal axis. The height of each bar represents the frequency, or the number of data points falling within that interval. Unlike bar charts, there are no gaps between the bars in a histogram since the data is continuous.

A bar chart is a graphical representation of data where rectangular bars are used to represent different categories or groups. The length of each bar is proportional to the value it represents. Bar charts are particularly useful for comparing discrete categories and understanding their relationships.