Adding icons to item types is something that you should do to make it easier to distinguish what types of items are shown in different views. Not only are the icons displayed in the views, they also provide a hover effect that tells which item type the icon represents if you put the mouse cursor on the icon.
Nektion provides a large collection of different icons to use for your item types. For example, if you had an item type called “Story” like the examples in this tutorial, an appropriate icon could be the “sticky note” icon.
To add icons, open the item type’s details view. Here, the row below “Name” says “Icon”.
Click the rounded square icon with a pencil drawn on top of it to open the icon catalogue. If you don’t find an appropriate icon from the first ones, try searching with different keywords. Once you’ve found a good icon, click on it and then press “Select” to confirm.