In evolutionary optimization, variation is the process of introducing diversity into the population of solutions. Like genetic mutations and breeding in nature, it involves altering the 'genes' (parameters) of candidate solutions to create new, different ones. This can be done through mutation (changing some parameters) or crossover (mixing parameters from two solutions). Variation is crucial for exploring new solutions and avoiding getting stuck with suboptimal ones, much like how biological diversity is key to the survival and evolution of species.

In evolutionary optimization, replication is like making copies of the best solutions. Imagine a survival contest where top performers are cloned. These copies then undergo changes (mutations) or combine features (crossover) to create new solutions. Replication ensures good traits are passed on, increasing chances that future generations will perform even better. It's used in algorithms to solve complex problems, where keeping and tweaking successful solutions gradually leads to finding the best or a very good answer.

In evolutionary optimization, selection is like a survival test for candidate solutions, deciding which ones get to 'reproduce.' Selection operators are the rules determining who passes this test. They might choose the fittest solutions (those solving the problem best) or sometimes include random or less fit ones for diversity.