Hi all,

This is my first post. I've really appreciated the informative and helpful advice provided by this community over the past while; and figured this is the best place to ask a two-part technical question concerning currency exchange. Here goes:

Firstly: How do exchanges (such as coinbase.com) convert crypto into actual, fiat currency?

Do they:

• Have multiple bank accounts with USD, EUR, AUD balances in them which automatically transfer when someone cashes out?
• Have an internal conversion capability whereby BTC / Cryptocurrency goes to whatever currency the customer decides?
• Rely on a third-party themselves to convert BTC / Cryptocurrency and then automatically transfer it to the customer's account?

Secondly: If I wanted to replicate this capability, how would I do it?
(I'm asking this because I'm curious as to how they technically implement this function. For example; if they have multiple bank accounts which deposit into customer's accounts at cashout, how is this automated / approved / allowed?)

Thanks in advance and kind regards!