Secondary metabolites in plants, such as cuticle and lignin, are not directly involved in growth and reproduction, distinguishing them from primary metabolites. The classification of metabolites as primary or secondary is not always precise, as it often depends on their prevalence across different organisms. Primary metabolites are universally present, while secondary metabolites are specific to certain types of organisms. This distinction highlights the diverse roles that these compounds play in plant biology, including defense mechanisms and ecological interactions. Understanding secondary metabolites is crucial for comprehending plant adaptation and survival strategies.