The crossover operator, also referred to as recombination, corresponds to the crossover that takes place during sexual reproduction in biology, and is used to combine the genetic information of two individuals, serving as parents, to produce (usually two) offspring.
The crossover operator is typically applied with some (high) probability value. Whenever crossover is not applied, both parents are directly cloned into the next generation.
The following sections describe some of the commonly used crossover methods and their typical use cases. However, in certain situations, you may opt to use a problem-specific crossover method that will be more suitable for a particular case.