# Which programming language is used by TikZ/PGF?

I've been playing with TikZ for while, and now I want to dig a bit deeper and produce some reusable components for future references. There are certain syntax that are used in many examples on TikZ site. For example I saw a `\foreach` loop, couple variables here and there. So I wonder which programming language is used to write `Tikz` document?

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