Java BigInteger.mod() is a method in the Java BigInteger class that returns the remainder of the division of two BigInteger objects. It is used for modulus operations in high-precision arithmetic, often found in cryptographic algorithms or large-scale numerical computations. Introduced in Java 2004 with Java 5, mod() ensures that the modulus operation maintains the precision of large numbers.

https://docs.oracle.com/javase/8/docs/api/java/math/BigInteger.html