How random numbers are generated in Programming languages? [duplicate]

This question already has an answer here:

• How does a random number generator work? 8 answers

I didn't find a similar question in the search engine and I actually wonder how random numbers are generated in Programming languages (What actually happens when I press these commands: Math.random(); or int r = rand();?) ? Is it the same way for every Programmning language? Is it a function that gets data from time and does a simple calculation? Thanks in advance. I hope it is a Programming question.