Ambigram is not only a form of word to word, but also can be read and written in different directions. Two way graphs can be composed of some words. There are many bidirectional graphs with different directions and the same type of words, but there are also two-way graphs with different directions and different characters. Douglas Richard Hofstadter, an American scholar, also described the bidirectional graph as "the calligraphic design that manages to squeeze two different readings into the selfsame set of curves.".

In short, the design that turns the text 180 degrees or projects with mirror image has considerable symmetry and can be read is called two-way graph. According to American designer John Langdon, the two-way map was developed by Langdon and Scott Kim, a Korean American designer, in the 1970s. Scott King published his first two-way atlas in 1981 under the title "inversions.". The first book that mentioned the word "ambigram" was written by houshida. Houshida was named bi-directional diagram only in the group of friends from 1983 to 1984.

Source: @linesnshadestattoo_studio_bhuj