Rule #263: Do not print images that are less than 300 ppi

Printing images can be tricky when it comes to resolution. If the images are not large enough they can print incorrectly, become blurry, and ruin a design all together. A good rule of thumb is to look at the screen ruling and double the amount (e.g. 150 lines per inch x 2 = 300 PPI).

Rule #255: Know the difference between similar, example, symbolic, and arbitrary icons.

Icons can be classified into four distinct categories, each with its own characteristics. Similar icons tend to be literal and depict simple objects, actions, or concepts, much like many road signs. Example icons, on the other hand, often represent complex actions in a single image, using symbols that are readily associated with a broader range of activities, such as an airplane for an airport. Symbolic icons are used when a recognizable shape can convey an action or concept, even if the image itself doesn’t literally represent it, such as a padlock for security. Lastly, arbitrary icons utilize imagery that requires learning to understand the meaning and may not have an immediate connection to the concept they convey.