Here is a paragraph of text with default line height. Line height is the vertical distance between the baseline of one line of type and the next. This distance is a proportion of the font-size.
The default line spacing is typically 1.2, but this paragraph has a tighter setting of .8, meaning the descenders of one line will touch the ascenders of the one below if they appear above one another.
This paragraph has a looser setting of 1.5. The font-size is 12 pixels and the line-height is 1.5 so the distance between the lines is 18 pixels. This gives an elegant look to your typography, but is a less efficient use of the vertical space.
A code example from Stylin’ with CSS, Third Edition by Charles Wyke-Smith. Visit stylinwithcss.com for more CSS information and updates.