Inform is when you want to show an important message or data point that doesn’t require much context to understand.  For example, you could make a numerical stat stand out with large, bold, colorful text, demand extra attention by pairing icons with text, or highlight a percentage or rate with a pie chart or pictograph.

Change is when you want to show trends over time or space.  Use a line chart or an area chart to show changes that are continuous over time.  You can use a timeline to show specific events in time.

Relationship is when you want to reveal more complex relationships among things.  Use a scatter plot when you want to display two variables for a set of data.  Use a multi-series plot when you want to compare multiple sets of related data.

Compare is when you want to show similarities or differences among values or parts of a whole.  You can use a bar chart, column chart, bubble chart or bubble cloud to compare independent values.  You can use a pie chart, donut chart, pictogram or tree map to compare parts of a whole.

Organize is if you want to show groups, patterns, rank or order.  You can use a list to show rank or order when you want to provide extra information about each element.   You can use a table to show rank or order when you want readers to be able to look up specific values.  You can use a flowchart to show order in a process.  You can use a mind map or Venn diagram to show organized groups.