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The Icon is a symbolic image that helps users quickly and simply identify the content
You can only set one icon Icon at a time
This component allows showing the Icon from the SLDS
You can refer to the documentation from SLDS https://www.lightningdesignsystem.com/icons/
e.g. Action icons, Custom Icons, Standard Icons, Doctype Icons, Utility Icons
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Using the Fill color you can apply solid color to the excess space of an image
e.g. The Icon is displayed in red if you enter that color
Fill color: Red