An icon can give users a hint about the button's purpose. Leading icons are commonly placed before the label in left-to-right languages. Research shows that in left-to-right languages, users scan pages, paintings, movie screens, and just about everything from the left.^[1] For this reason, placing an icon on the left helps identify a button and its purpose much faster. When it appears after a button label, the icon serves only as decoration.

Additionally, placing your icons on the left will leave room on the right for a downward pointing arrow when you need a dropdown menu.

If icons are self-explanatory and recognizable, users won't need to read the label. Use a leading icon to grab their attention.