How much does Coinbase charge?

As a cryptocurrency enthusiast, I'm curious about the costs associated with using Coinbase, a leading digital currency exchange. Could you elaborate on the fees Coinbase imposes on its users? Specifically, what are the transaction fees for buying and selling cryptocurrencies? Are there any additional charges for deposits, withdrawals, or account maintenance? Furthermore, does Coinbase offer any discounts or promotions for frequent users? Understanding these details is crucial for making informed decisions when it comes to managing my digital assets.