Selection Method: Parents are selected according to their fitness. The better the chromosomes are, the more chances to be selected they have.

Roulette Whell:  With this selection method, the chance of a chromosome to be selected is calculated according to their fitness (cost) or according to their rank. 

Tournament:  With this selection method, a small subset of chromosomes is selected and the one with the best fitness will become a parent.

Top Mate: The first parent is selected by the fitness order. The second parent is selected randomly.