K and Q are the languages behind KDB. K is the lower-level language and is a variant of APL. Q is the higher-level one, bringing in elements of SQL. J is anot

K and Q are the languages behind KDB. K is the lower-level language and is a variant of APL. Q is the higher-level one, bringing in elements of SQL. J is another APL-like programming language, unrelated to KDB, by the actual creator of APL. All are easy to google by adding "programming language" to your query, and each has a wikipedia page.