What are best practices for form design, label placement, and inline validation?

Label placement: Top-aligned labels (above the input field) are the SLDS default and best practice. They reduce eye movement, work well on mobile, and are faster to complete than right-aligned or left-aligned labels (Nielsen Norman Group research shows top-aligned labels reduce completion time). Avoid placeholder text as the only label — it disappears on focus and fails accessibility requirements. Inline validation: Validate on blur (when the user leaves the field), not on every keystroke — real-time validation creates anxiety. Show success states for important fields (green checkmark) to build confidence. Display error messages directly below the field with a clear icon and specific guidance: "Enter a valid email address (e.g., name@company.com)" not just "Invalid input". Error messaging: Be specific, blame the system not the user, and always provide a path to resolution. Required field indicators (*) must be explained at the top of the form. Group related fields visually. Keep forms as short as possible — ask for data only when truly needed.