Greeking

If text gets smaller than this value, [Adobe] Illustrator shows the text blocks as gray bars, an operation called greeking. Both type size and view size figure into the equation, so that 6-point type greeks at 100-percent view size and 12-point type greeks at 50 percent. Greeking speeds the screen display because gray bars are easier to draw than individual characters.

Designers have long worked with a concept known as greeking. Greeking is a method of drawing gray bars to represent blocks of text rather than taking the time to image them all on the screen. […] Unless you really want to see every character of every word at every size, there's hardly any reason to turn greeking off.

The use of greeking (also called dummy text) allows page designers to place text on a page without the actual content acting as a distraction. The history of greeking is unclear, but it was first used in the middle of the 20th century. The text was based on the words of Cicero, a Roman leader whose writings are admired. The language he spoke and wrote was Latin rather than Greek, so the naming of this dummy text is misleading.