Erik Erikson's stages of development is a theory that outlines eight key conflicts individuals face throughout their lives. Each stage represents a critical period where a person must resolve a challenge to develop a healthy personality. These stages range from trust vs. mistrust in infancy to integrity vs. despair in old age, highlighting the importance of social relationships and personal growth. Each stage builds on the previous one, meaning unresolved conflicts can affect future development. Erikson emphasized that successful resolution leads to a stronger sense of self and better relationships, while failure can result in difficulties in later stages of life.