Puppy development occurs in several stages, starting from birth to around 18 months. During the first few weeks, puppies are entirely dependent on their mother for warmth, food, and care. As they grow, they begin to open their eyes and ears, explore their environment, and interact with their littermates, which is crucial for socialization. Around 3 to 12 weeks, puppies experience a critical socialization period. This is when they learn important behaviors and skills by interacting with humans and other animals. Proper exposure to various sights, sounds, and experiences during this time can help shape a well-adjusted adult dog, making it essential for new puppy owners to provide positive experiences.