K and the more comprehensible Q are languages created by Artur Whitney based on APL. Kdb+ is the database system and interpreter for these languages. Kdb+ allows extremely efficient analysis of high-volume real-time and historic data simultaneously in a column based database. At $100,000 per Dual-Core Processor license, K is absurdly priced and only affordable for large financial institutions and the United States military. K is a vector based language with analogies to mathematics and human language. Nearly every character represents either a noun, verb, or adverb allowing extremely terse and efficient development and processing for those who are able to wrap their heads around the syntax.
K is powerful enough that an experienced quantitative analyst with the full range of tools could go from an idea, to a full tick-level back-test, to a fully deployed trading system in under an hour.
While this product is unfordable to nearly everyone in its full form, Kx Systems has released a limited version of the software free of charge. I highly recommend anyone interested in computer languages, analysis, finance, etc. to download and explore this amazing software which takes less than 200 KB on disk including the interpreter, an http server, and socket connectivity!
As a final note for those with a particular interest in providing programming services, it is our understanding that a capable K programmer averages about $250,000 per year working for a large investment institution.