Emacs sometimes displays clickable buttons (or other informative icons), and you can customize how these look on display.
The main customization point here is the
option. By using this, you can tell Emacs your overall preferences
for icons. This is a list of icon types, and the first icon type
that’s supported will be used. The supported types are:
Use an image for the icon.
Use a colorful emoji for the icon.
Use a monochrome symbol for the icon.
Use a simple text for the icon.
In addition, each individual icon can be customized with M-x customize-icon, and themes can further alter the looks of the icons.
To get a quick description of an icon, use the M-x describe-icon command.