It's not "bad" for the eyes, it's apparently easy on the eyes if you use a Sans Serif font as opposed to the Times New Roman font. Sans Serif fonts don't have feet whereas Times New Roman fonts do...
Read on...
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Fonts
This might sound crazy, but words are for more than just reading. The shape and appearance of a word can say as much as the word itself can. That’s why it’s important to use fonts well. Here are some rules
How many different fonts are used? Count them. If there are more than three, then the design piece is dangerously close to being labeled bad. Good graphic design usually employs consistency and restraint in choosing fonts: one for the headers, one for the body text, and a third for special accents. Any more, and you risk losing your audience in a sea of confusing textual clutter.
The use of fonts should be imaginative, original, and purposeful. Fonts are often a great opportunity to add life to a piece of Graphic design. If a work is using common fonts like Arial, Verdana, and Times New Roman, that instantly loses a few points for being boring and uninspired. Those fonts are great for e-mail and letter writing, but don’t attract attention or provide much excitement.
Look for fonts that mix well with the message. Serious communication requires a serious, authoritative look. Weird bands that usually play late at night in obscure locations require fonts that are confusing and hard to read. This seems to be a general rule.
Look for correct usage of Serif and Sans-Serif fonts. A Serif font is a font with small “feet” on the letters. Times New Roman is a Serif font, and is well suited to body text, as the feet on the letters help your eyes to follow along the words. Almost all published books use Serif fonts, because it’s easier on the eyes. A Sans-Serif font like Arial does not have “feet” ,and is a good headline font because it’s big and bold and calls out from a distance.
Fonts should be easy to follow, and should attract your attention. Hopefully, a designer will choose a font with a personality that fits well with the other elements of the project. When this is done properly, the message is powerful. When it’s done poorly, the piece will struggle to say what it means.
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Change the Default Font
On your browser menu, choose: Tools -> Internet Options -> General -> Fonts
There will be two choices, Web Page and Plain Text. Arial and Verdana are both clean, modern and easy to read. Times New Roman is elegant. Try a few and select one you like. Courier is usually the only choice for the Plain Text Font.