I have multiple currencies in my org. My Advanced Currency Management is not enabled. Now when I am creating any custom object, I can see that Currency is coming as Standard field on every object automatically. And due to that while creating a new record of that object, I have to choose currency always. (I can definitely remove currency from page layout though). But what I am not getting is that why currency is coming as Standard field automatically to every custom object? Any idea guys.
Since you have multi-currency on in the org, this causes the field to be added to all the objects. See the implications of enabling multi-currency.
Upon enablement, all existing records are stamped with a default currency code that you provide in your enablement request. For example, if your organization contains records using USD and EUR, you need to switch them all to the same default currency prior to enablement. Support for this type of conversion is also available as a salesforce.com paid implementation service.
Advanced currency management controls dated exchange rates, it has nothing to do with the currency field.