Mersenne Twister is a non-cryptographic RNG that's commonly used in many applications. According to Wikipedia:
The Mersenne Twister is the default PRNG for the following software systems:
Microsoft Visual C++,[3] Microsoft Excel,[4] GAUSS,[5] GLib,[6] GNU Multiple Precision Arithmetic Library,[7] GNU Octave,[8] GNU Scientific Library,[9] gretl,[10] IDL,[11] Julia,[12] CMU Common Lisp,[13] Embeddable Common Lisp,[14] Steel Bank Common Lisp,[15] Maple,[16] MATLAB,[17] Free Pascal,[18] PHP,[19] Python,[20][21] R,[22] Ruby,[23] SageMath,[24] Scilab,[25] Stata.[26] It is also available in Apache Commons,[27] in standard C++ (since C++11),[28][29] and in Mathematica.[30] Add-on implementations are provided in many program libraries, including the Boost C++ Libraries,[31] the CUDA Library,[32] and the NAG Numerical Library.[33]
Mersenne Twister is a very good PRNG, with good statistical properties, very long period, and is fast. Despite being a very good PRNG, and is widely used for many games, statistical simulations, and other purposes, it's not suitable for cryptography.
Another common RNG is linear congruential generator (LCG), which for a long time is the default RNG in popular C libraries (and many other languages that uses C library, such as PHP). LCG is a simple but very poor RNG, even for non-cryptographic RNG standards. Its period size is embarrassingly small, already-produced numbers cannot repeat for the entire period, and it has statistical properties that makes it unsuitable for many purposes.