I think we know about alt-texting (provide a description alternative) images. But if you don't, you should alt-text .your charts because when a screen reader reads the image, it needs to convey the message of what the image is showing so that you can create a comparable experience.
Do you know what Tableau generates for the alt-text in a chart if you don't change it? Check out the example below the map I have in a dashboard.
I don't know about you, but Shape chart of Location Log Location Lat doesn't exactly convey the insights or the data effectively.
To change the alt-text, you can either navigate to the drop down arrow for the chart on the dashboard or use the Worksheet menu to navigate to Accessibility.
There are a few pieces of advice out there on how to write an alt-text description. I'm a fan of doing what works for you. Amy Cesal wrote this great piece about alt-texting charts.
I'll share my approach in case it's helpful for anyone else.
To describe a chart, write what you would tell someone when describing the chart to them.
I used this approach to describe the plots on my map.
If you have a publishing process or checklist, don't forget to add alt-text charts to that list to help people have a comparable experience between the screen reader and visual experience.