Autobiographical memories are simply memories about our own experiences. These are by are the most fascinating type of memories. We often use these memories to entertain each other. Some people even publish them.
One aspect of autobiographical memory is that most adults cannot recall any event from before ages four or at least three years of age. If the occasion was significant enough, some adults have been known to remember events as early as 2 years of age, but no matter how important the event, it is seemingly impossible to remember prior to age 2. This inability to remember prior to age 2 is often called childhood or infantile amnesia.
Some memories do exist from the toddler years. These are procedural memories. How to do things like use a fork, drink from a cup, pull a wagon, etc. Semantic memories acquired early in life are also retained. These are such things as the rules of counting, the names of people and things, knowledge about objects in the world, words and meanings. As toddlers of only 1-2 years old, many can remember past experiences and many 4-year-olds can remember experiences that occurred before age two and a half, but these memories fade with time. The reason is that young children do not encode and retain their early episodic memories, the memories of particular events, and carry them into later childhood or adulthood well.
Psychology 7th Edition by Carole Wade and Carol Tavris
Class notes from Psychology 101