Common practices and guidelines for setting type in Web design. Note, though, that these findings are not scientific and should serve only as rough guidelines:

1. Either serif or sans-serif fonts are fine for body copy and headings, but sans-serif fonts are still more popular for both
2. Common choices for headlines are Georgia, Arial and Helvetica
3. Common choices for body copy are Georgia, Arial, Verdana and Lucida Grande
4. The most popular font size for headings is a range between 18 and 29 pixels
5. The most popular font size for body copy is a range between 12 and 14 pixels
6. Header font size ÷ Body copy font size = 1.96
7. Line height (pixels) ÷ body copy font size (pixels) = 1.48
8. Line length (pixels) ÷ line height (pixels) = 27.8
9. Space between paragraphs (pixels) ÷ line height (pixels) = 0.754
10. The optimal number of characters per line is between 55 and 75, but between 75 and 85 characters per line is more popular
11. Body text is left-aligned, image replacement is rarely used and links are either underlined or highlighted with bold or color.

Of course these “rules” aren’t set in stone. Rather, they are a set of rough guidelines that you can use as a basis for setting typography. Every website is unique, and you may want to modify your choices at each stage of your design to suit your layout. You can also take a look at the spreadsheet of the study and export its data for further analysis.