how is exp(x) calculated?

I'm doing a project in a matrix methods class about approximating the exponential function using various methods, and I wanted to do a section about how the function is calculated in various coding softwares.

Does exp(x) use a polynomial approximation? If so, what degree? Is it domain-dependent?

If not, what is used?

[AJ Biffl]

Also, if anyone knows similar info about other coding softwares ex. Mathematica, Java, Javascript, or Python, that would be super helpful

[Walter Roberson]

https://math.stackexchange.com/questions/18445/fastest-way-to-calculate-ex-up-to-arbitrary-number-of-decimals

https://www.quinapalus.com/efunc.html

http://www.mlb.co.jp/linux/science/yacas/documentation/Algochapter4.html