When you are writing an eBook, special or short report, sales letters or web copy, or anything that will be read online, it is best to use san serif fonts. Even though these fonts are more difficult to read, they are still considered to be the most effective online, especially for headlines, captions, and other short lines of text.
The terms serif and san serif come from long along, when typesetting was used to print newspapers and other documents. Serifs are the small lines that appear at the end of letters, numbers, and other characters. The word sand means without, so sans serif typefaces are those fonts that are without these small lines. The most popular serif fonts are Times New Roman, Courier, and Palatino. Popular sans serif fonts include Arial, Tahoma, Verdana, and
When I am writing sales letters I like to use 16 point Tahoma for my headlines and 12 point Arial for the remainder of my web copy text. This seems to be more appealing to the readers and have a higher conversion rate for views to sales. Of course, this will continue to be highly debated for years to come, so you will want to do your own testing based on your niche market and type of product or service you are selling.
For eBooks, I like to use a combination of 14 and 16 point font size for titles and sub-titles, and 12 point font size for the body of text. Again, I prefer Tahoma or Verdana for the titles and sub-titles, with Arial as my preference for the text body font. Experiment with your eBook content and see what is easier on the eye. Take a look at other eBooks you have purchased and pay close attention to the fonts used.