ROT13 is a simple Caesar cipher for obscuring text by replacing each letter with the letter thirteen places down the alphabet. A becomes N, B becomes O and so on. The algorithm is used in online forums as a means of hiding joke punchlines, puzzle solutions, movie and story spoilers and offensive materials from the casual glance. ROT13 has been described as the "Usenet equivalent of a magazine printing the answer to a quiz upside down". ROT13 originated in Usenet Internet discussions in the early 1980s, and has become a de facto standard. As a Caesar cipher, ROT13 provides no real cryptographic security and is not used for such; in fact it is often used as the canonical example of weak encryption. Because ROT13 scrambles only letters, more complex schemes have been proposed to handle numbers and punctuation, or arbitrary binary data.

Read the rest of this article: http://en.wikipedia.org/wiki/ROT13

Today's selected anniversaries:

1783 Jean-François Pilâtre de Rozier and François Laurent made the first untethered hot air balloon flight. (http://en.wikipedia.org/wiki/Hot_air_balloon)

1877 Thomas Edison announced his invention of the phonograph. (http://en.wikipedia.org/wiki/Phonograph)

1969 The first ARPANET link was established. (http://en.wikipedia.org/wiki/ARPANET)

2002 NATO invited Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia to become members. (http://en.wikipedia.org/wiki/NATO)

Wikiquote of the day:

"The one important thing I have learned over the years is the difference between taking one's work seriously and taking one's self seriously. The first is imperative and the second is disastrous." ~ Margot Fonteyn (http://en.wikiquote.org/wiki/Margot_Fonteyn)