What is Coinbase GDAX?

Could you elaborate on what Coinbase GDAX is and its significance in the cryptocurrency market? As a professional in the field, I'm curious to understand how it differs from other exchanges and what specific features or services it offers that make it stand out. I've heard it mentioned frequently but would like a more in-depth explanation of its role and functionality. Additionally, I'm interested in knowing if there are any specific regulations or compliance measures Coinbase GDAX adheres to, ensuring the safety and security of its users' transactions.