Chord charts or chord diagrams are used to display relationships between data in a table. They are know as chord charts since a chord in geometry is a line that connects two endpoints on a circle.
Below is an example of a chord chart showing import and export data between the world's top 6 economies. :
The chord chart illustrates trade between the 6 economic powerhouses. Selecting on one of the countries shows trade relationships for that given year. For instance of the 6 countries above, China Exports the most to the US, followed by Japan.
The above chord charts was made with this csv file, which includes all countries. To make the chart above the data was filtered in POWER BI to include only the top 6 Economies. See data file here: