Readability [ree-duh-bil-i-tee]
The state or quality of being readable. Typography. The property of type that affects the ease with which printed matter can be read for a sustained period.

Legibility [lej-uh-bil-i-tee]
Also leg·i·ble·ness. The state or quality of being legible.
Also called visibility. Typography. The quality of type that affects the perceptibility of a word, line, or paragraph of printed matter.

How readable is your message? Just like good design helps a message to connect with your audience, so does readability. There are some fonts that we only use for headlines; they are classified as “display” or “script” fonts. They have personality and can add flair. But, it’s critical to use in small doses, especially if the majority of your audience is over 40. I learned this early in my career before my eyes started revolting. It was a 40-something boss who explained this to me. I was typesetting a letter to go out to our patrons; it was clean with a lot of white space. However, my 9 point text and the lightweight font was not reader-friendly to the audience that would receive it. So, even though I read it perfectly well with my 20-something eyes, I learned that I was not the end user. And that was when it clicked; it’s not about me, which is now what I preach to my clients. It’s not about us or what font we like. It’s about the donors and patrons. They matter more and if they cannot read what we send, how is that helpful?

Of course, we can add flair in other ways and use fun fonts for headers, but we have to consider how the information is sent. It used to be easier when you sent things on real paper in the mail. Now you have to think if the email will be read on a tiny phone or a desktop or a tablet. The weight and color of the text might read really well on your desktop but not on someone’s phone. I recommend sending tests and seeing how it reads on different devices and then asking your colleagues or family (of various ages) to give it a look and watch their reaction. It’s a helpful gauge, and you get to see it on multiple devices because it makes no sense to send something that is unreadable to half your intended audience.