Why does Coinbase put a hold on my balance?

Could you please elaborate on why Coinbase decides to put a hold on users' balances? I've recently noticed this happening with my account and I'm curious about the reasons behind this practice. Is it a standard security measure or are there specific factors that trigger this action? I'm particularly interested in understanding if this is a common occurrence and what steps Coinbase takes to ensure that the holds are justified and lifted as soon as possible. Any clarification would be greatly appreciated.