Companion planting is a gardening technique where different plants are grown together to enhance growth, deter pests, and improve flavor. For example, planting basil near tomatoes can boost the tomatoes' flavor and help repel harmful insects. This method takes advantage of the natural relationships between plants, creating a healthier garden ecosystem. By choosing the right plant combinations, gardeners can reduce the need for chemical pesticides and fertilizers. Some plants, like marigolds, are known to attract beneficial insects while repelling pests. Overall, companion planting promotes biodiversity and can lead to a more productive and sustainable garden.