When you use My dear instead of Dear?

"My dear" is often used as a term of endearment or affection, conveying warmth and intimacy, while "Dear" is more formal and can be used in a variety of contexts, such as letters or emails. You might choose "My dear" when addressing someone close to you, like a friend or family member, to express fondness. In contrast, "Dear" is suitable for professional or polite correspondence where a more neutral tone is appropriate.