The human brain is generally considered fully developed around the age of 25. This is because the prefrontal cortex, responsible for decision-making, emotional regulation, and impulse control, finishes maturing around this time. However, brain development is a complex, ongoing process. Structural growth mostly tapers off in the mid-to-late 20s, but the brain remains plastic, meaning it continues to rewire and adapt throughout life in response to learning and experiences. Some research suggests that brain development, including refinement and connectivity changes, may continue beyond 25 and up to around age 30. Additionally, there is significant individual variability, meaning some people's brains might mature earlier or later than average. In summary:

• Major structural brain development slows down and largely completes by the mid-to-late 20s.
• The prefrontal cortex is the last part to mature, around age 25.
• Brain plasticity and adaptation continue lifelong.
• Some studies show brain development and maturation processes can continue until about age 30.

Therefore, your brain stops developing structurally around 25 to 30 years old but remains capable of change and adaptation beyond that range.