How much does Coinbase charge per transaction?

Can you please clarify for me the fees that Coinbase imposes on each transaction that occurs on their platform? Are these fees a fixed amount or do they vary depending on certain factors such as the size of the transaction, the type of cryptocurrency being traded, or the level of activity on the platform at the time? Additionally, does Coinbase offer any discounts or promotions for users who execute a high volume of transactions or maintain a certain balance in their accounts? It would be greatly appreciated if you could provide a concise yet comprehensive answer to these questions.