It's a somewhat esoteric, and extremely terse, language used by some financial modeling firms. Influenced heavily by APL, but (thankfully!) without the non-ASCII characters.

https://en.wikipedia.org/wiki/K_(programming_language)

k and q are array languages in the APL tradition. APL is one the "ur programming languges". https://madhadron.com/programming/seven_ur_languages.html

Here's an open source implementation of k: https://codeberg.org/ngn/k/

kdb is a time-series database with deep integration to k. It is famously used in the financial industry.

k: super terse language inspired by APL and lisp

q: slightly less-terse language written in k, with similar semantics. The vendor (kx) supports q, not k

kdb+: column-oriented database bundled with q

Came here to ask the same. kx.com is just some marketing page. I still have no idea what kdb+/k/q is.

Skip all the marketing materials & go to the dev pages - https://code.kx.com/q/learn/install/