Bank

Gold can be deposited into or withdrawn from your bank account by speaking to bank NPC's in any major city using the 'deposit' and 'withdraw' commands and specifying the amount.
Gold is taken directly from your bank account when purchasing any items or paying for services from in-game NPC's, buying player Houses or when your monthly gold house rent is due.
The Gold Pouch can be used to deposit gold directly into your bank account by right-clicking as well as withdraw gold wherever you are without the need of a bank NPC.