Say there's an online wallet or exchange or some site, and they give me an address to send my bitcoins to.
I get the public address but not the private address because technically those bitcoins are now "theirs" - and i'll use them to exchange for other crypto currencies at some time.
But the public address is listed on sites like blockchain.info and I can see all of my transactions to that wallet.
Is it normal to see transactions going out of that wallet, even if I haven't spent those bitcoins with the service? Is my wallet isolated to transactions I might conduct?
Or do they use a normal bitcoin server, so whenever anyone withdraws, it uses whichever bitcoin transactions are available in this company's entire collection based on their bitcoin servers algorithms using all the accounts listed?
In theory, it shouldn't matter, so long as the total amount in everyone's accounts is equal to the total amount in all of the private keys they maintain. But do any of the services keep them isolated as sort of a check to make sure that a customer's coins are still there and it's not some type of ponzi scheme?