If text feels hard to read, people won’t want to read it. One factor that affects readability, and a great place to start, is choosing a legible font.
Top: Helvetica 14/20 on a 1280×800 MacBook Air screen. The text is readable, but clunky. Letters feel tight, and the letter e closes up into a circle. Bottom: Georgia 14/20 on a 1280×800 MacBook Air screen is a bit easier to read. Words and letters are more clear, allowing the eye to move quickly along the line of text.
1 descender; 2 baseline; 3 length of descender; 4 serifs; 5 stem. Top: Georgia is a serif font, because it has serifs. Bottom: Helvetica is a sans serif font because it doesn’t have serifs.