The standard monetary unit throughout the Oikumene is the Standard Value Unit (SVU or "Sol", after the Bank of Sol who first standardized the unit). The SVU has a value equivalent to one hour of unskilled labour in normal conditions, and its value is constant throughout the Oikumene. That is not to say, however, that goods or services will cost the same throughout space - some places are more expensive than others.
An unskilled labourer, therefore, will make 8svu in a standard working day, (roughly 2,000svu per year). If he or she is being paid less, then s/he knows that the work is being undervalued. Likewise, an executive who is making 400svu per week can rest smugly in the knowledge that he or she is worth ten proles any day.
Money exists primarily as electronic transfers between banks and other financial organizations, via a credit chip which is dedicated to an individual account holder identified by genetic information. Only the person identified according to this information (or their properly authorized representative) is able to access the resources of the account through the chip. This is the safest and most popular method of making commercial transactions. It has the disadvantage of requiring communication with the bank (or bank's agent) to make a transaction.
Money can also be transferred in the form of physical certificates of credit, which allow the holder to draw on the reserves of a given financial institution (normally the Bank of Vega, Bank of Rigel or the Bank of Sol) up to a stated limit. This is perfectly legal, but isn't encouraged by most authorities since it leaves no electronic signature to a transaction. The portability of the system makes it ideal for use in remote areas, while the anonymity provided by the use of the notes make them popular for furtive transactions such as the purchase of a copy of "One Thousand Country and Western Greats".
The certificates of the three above-mentioned banks can be tested for authenticity by use of a very common device known as a Fake-Meter. These are available almost anywhere at a very small cost. They are small, fitting easily into a pocket, and feature a slot through which a note is passed; a genuine note returns a soft bell-like tone, while a counterfeit causes a warning buzz. The internal workings of the meters self-destruct if the integrity of the casing is compromised in any way. Exactly what the meters actually measure is a question to which many people would like to find the answer.