The preoperational stage, Piaget's second stage of cognitive development occurring from approximately ages 2 to 7, is characterized by the use of symbols to represent words, images, and ideas. This symbolic thinking enables children to engage in pretend play and develop language skills. However, their logic is intuitive and based on personal knowledge rather than conventional reasoning. The stage is termed 'pre-operational' because children cannot yet perform logical operations or mentally manipulate information, a key limitation demonstrated by their difficulty with the concept of conservation.