What makes you the same particular person over time?

What is the Self? What makes us human, and which part of you is the real you? What makes you the same particular person over time?

Potential considerations: Is the human self the soul (or mind), body and soul together, just the body, or something else? Is the mind just the brain, or is it something separate (like a soul)? Is reason what makes us human, or is it some other aspect? Regarding your particular self, is identity based on experience, consciousness, or something else? What makes you the same person over time? Which question do you think is more important, what we are, or who we are? Why? Feel free to bring in any other relevant potential considerations.