import re


def mask_pii(text: str) -> str:
    """Mask Personally Identifiable Information"""
    # Email addresses
    text = re.sub(r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b', '[EMAIL]', text)
    
    # Phone numbers
    text = re.sub(r'\b(?:\d{3}[-.]?\d{4}|\d{3}[-.]?\d{3}[-.]?\d{4})\b', '[PHONE]', text)
    
    # Credit card numbers
    text = re.sub(r'\b\d{4}[- ]?\d{4}[- ]?\d{4}[- ]?\d{4}\b', '[CREDIT_CARD]', text)
    
    # Social Security Numbers
    text = re.sub(r'\b\d{3}-\d{2}-\d{4}\b', '[SSN]', text)
    
    return text