The Rule of Three is prevalent in many fields. There are two fields of thought on the reason: 1) it is because we humans have become proficient at pattern recogonition and three is the smallest number of elements required to create a pattern, and 2) because the mind finds symmetry in odd numbers, but it can rarely remember more than 3 things it has seen or heard.
When creating your next ad, flyer, brochure, business card, or any promotional material, remember the following Rules of Three:
1. Three font colors are the most that should be used in any media presentation.
2. Limit your usage of font types to 3 - including bold and italics.
3. Bullet items or a list of items should be limited to 3 points or details.
When it comes to font types and font colors, more than 3 of each, and your mind will see it as "busy" and "too much effort" to read - these are not the feelings you want to present to your reading audience.
The Power of the Rule of Three
How powerful is the Rule of Three? Very powerful indeed, as lists of three and 3 worded slogans have been used from very early in human history up to the present day. Lists of three are used by politicians and advertisers to sell their ideas; we have all heard the following and they still make an impact on us today:
Stop, Drop, and Roll - Fire Safety
Mind, Body, Spirit - describing the complex facets of being human
"Friends, Romans, Countrymen lend me your ears" - William Shakespeare play
Less is more - the notion that simplicity and clarity is the best alternative
Just Say No - Anti-drug Slogan
"Life, Liberty, and the Pursuit of Happiness" - US Declaration of Independence
Of course, there can be exceptions, but the Rule of Three is an easy way to make sure that your audience is not overwhelmed by the number of font colors, font styles, and large lists...overwhelm your audience, and you've lost them - and their business.