wikipedia‘s definition is:
A sparkline is a very small line chart, typically drawn without axes or coordinates. It presents the general shape of the variation (typically over time) in some measurement, such as temperature or stock market price, in a simple and highly condensed way.
Andy Kriebel took the time to create and upload a couple of good sparkline videos:
Ryan Sleeper wrote this article:
Andy Kriebel wrote this excellent, comprehesive article:
This blog post on Tableau Public by Jim Wahl is equally impressive:
Adam McCann devised an exiting new combination of bar charts and sparklines in February 2017:
That last blog post incorporates a downloadable workbook, and the second example I’m sharing is one of Andy Kriebel’s, where he looks at the race for Republican nomination: