After college, Langdon worked at Walter T. Armstrong Typography "setting headlines for
ad copy" and attended drawing, painting, and advertising classes at
Philadelphia College of Art in the evenings. By 1980, Langdon claims both he and
Stanford graduate student
Scott Kim invented ambigrams, albeit separately. Kim called his creations inversions; in 1984,
Douglas Hofstadter coined the term ambigram. Langdon uses mathematics, particularly
Fibonacci sequences,
bell curves, and
normal distribution to "explore relationships of everyday objects and situations that often go unnoticed". In 1992,
Three Rivers Press published
Wordplay, Langdon's first book about ambigrams. Each ambigram was accompanied by a philosophical essay. Math professor Dick Brown contacted him with questions about his craft and also asked if he would be interested in designing a cover for his son
Dan's new album,
Angels and Demons. Langdon later created the animated title for
The Da Vinci Code film as well as the logo of the Depository Bank of Zurich, a fictional bank in the movie. In 2007, Langdon and fellow graphic artist Hal Taylor won an award from the
Type Directors Club for their font Flexion. Two years later, along with Jason Santa Maria,
Khoi Vinh, Liz Danzico, and Dan Cederholm, Langdon created Typedia, a
wiki-style font library. In 2012, he put on an exhibition that showed word paintings based on
Rorschach tests. Over the course of his career, Langdon has done work for
John Mayer,
Aerosmith,
Sony Pictures,
DirecTV,
Nike, and
Will Shortz, among others. His work has also been featured in
U&lc Magazine,
Letter Arts Review, and in the Type Directors Club annual. Langdon has provided design criticism for magazines such as
Critique; forewords for books such as
The Art of Deception by Brad Honeycutt and
Eye Twisters by
Burkard Polster; and prefaces for publications such as
Calligraffiti by
Niels Shoe Meulman. He has been a member of the Type Directors Club, the Society of Scribes, and
The One Club. ==Personal life and death==