Setting Web Type to a Baseline Grid
http://dev.opera.com/articles/view/setting-web-type-to-a-baseline-grid/

Grannell, Craig
Opera
2008

Abstract:

This article covers the basics of baseline grids—defined grid areas within which content is placed—and how they can be applied effectively to the web medium. In print, baseline grids are almost mandatory. They ensure the bottom of each line of text—its baseline—aligns with a vertical grid, akin to writing on a ruled piece of paper. With books, this means text is always in the same position on the page. This ensures the gaps between lines of text aren’t “filled” with content showing through from the reverse of any page, thereby making the text easier to read. This advantage isn’t relevant for Web design, but the other major advantage—maintaining a vertical rhythm—is.