These groups are known as Greek letter societies or as being part of the Greek system.

VOA: special.2009.09.25

Daisywheel divides the alphabet into eight groups of four, assigning each letter to a controller face button based on the position of the left-analog stick.

ENGADGET: Steam Big Picture beta hands-on HD

Many of the groups that signed the letter were instrumental in securing a moratorium on geo-engineering research under the U.N.

FORBES: Green Groups Blast U.N. Climate Panel for Alarmism

"These pages and images are approved by your moderators, while you regularly remove content such as pictures of women breastfeeding, women post-mastectomy and artistic representations of women's bodies, " read the letter, signed by dozens of women's groups from around the world.

CNN: Under pressure, Facebook targets sexist hate speech