English is read from left to right, but are some languages written from right to left or from top to bottom?

News flash: Twitter now comes in 28 languages – including Arabic, Farsi, Hebrew, and Urdu, which are written from right-to-left. Twitter has long supported right-to-left text from users, but it now has instructions and can display hashtags from right-to-left as well.

Why are some languages written from right to left and others from left to right? Let’s start at the beginning – 3500 B.C. At least that’s typically when scholars acknowledge that writing began, or more specifically, when the writing system known as cuneiform began to emerge. Other forms of writing, like Egyptian and Indian hieroglyphics, predate cuneiform, but cuneiform was different because it started to use abstract shapes to represent sounds. Rather than using an image of a bird to represent bird, as hieroglyphics does, cuneiform used markings to represent the sound “ah” or “sa.” This was a big leap in writing systems because it was the development of a phonemic alphabet, in which letters represent sounds.

The biggest advantage of using letters instead of symbols is how many figures you need. If every word was a symbol, we would need thousands and thousands of symbols, but because we can make sounds out of letters and those sounds correspond to the words we speak, an alphabet becomes much easier to use. This is what happened with cuneiform. Early on it had thousands of symbols, but over time as the symbols became more representational and less literal, fewer were needed.

Early on in its development, cuneiform was written from left to right. It has been hypothesized that this is because right-handed scribes would smudge their work if they wrote from right to left. There is little historical evidence for this hypothesis.

Why would you compile a dictionary of an extinct language? Read about the Assyrian dictionary here.

How and when specific languages started writing from right-to-left is still under debate. For example, Persian (which is a descendant of cuneiform) is written from right-to-left, even though its predecessor is not. This may be from particular historical circumstances, but there is no academic consensus on the exact reasons.

Both Arabic and Hebrew came from the Proto-Canaanite alphabet, which was written from right to left. Proto-Canaanite was also sometimes written in a hybrid form called boustrophedon in which the directions of the lines alternate. One line is written right to left, and the next line is written from left to right. This is easier on the scribe, but not necessarily on the reader. This writing style was used sporadically in Greek and Latin, particularly in religious inscriptions.

Because they are based on characters rather than letters, Chinese and Japanese can be written horizontally or vertically. Traditionally, Chinese was written in vertical columns with the text starting in the top right corner of the page, running down and then to the left. Today, Chinese has mimicked the direction of English and is more commonly written in rows starting from the top left corner, written from left to right and down the page.

By including right-to-left languages, Twitter is making the Internet a more non-English-friendly place. Read an interview with a Twitter localization manager here.

What do you think about this change?