What are icons? Why not only use text? It's less work, and easy.
An icon is
An icon is a tiny symbol that is universally understood. At least some of them. Wherever and whoever you are. A house means home, an arrow means direction.
But what when an icon has to explain something that doesn't exist, or fit your style?
To say much with little
An icon can say much with little. It should be easy to read on anything. From small badges to large signs. A lot of care goes into designing good icons. Probably more than what you see.
Below you can see some icons that I've created. For various purposes. They're part of an icon set, or iconography if you want to be fancy.