Kenneth E. Iverson developed APL at IBM and described it in his 1962 book A Programming Language.
APL is named from the book’s title and is known for a compact notation using many specialized symbols. Iverson designed it to express mathematical ideas clearly and concisely, rather than to resemble conventional English-like programming syntax.
APL later became associated with interactive array programming. Its operators work naturally on whole arrays, which lets a short expression perform work that might require many lines in another language. This made APL influential in numerical computing, education, and data analysis.
A common mix-up is confusing APL with J. J was created later by Kenneth Iverson and Roger Hui as an ASCII-based descendant, because ordinary keyboards could not easily provide APL’s distinctive symbols.