Currency glossary

The terms used on the exchange rate pages, defined in one or two sentences, with a source where the term is official.

Reference rate: A rate published by an authority or a data provider as a snapshot of the market at one point in the day. It is meant for comparison, accounting and information. It is not an offer: nobody has to trade at it.; Banco Central Europeu — Euro foreign exchange reference rates
Cross rate: A rate between two currencies worked out through a third one. The European Central Bank quotes everything against the euro, so a rate between two non-euro currencies is one euro rate divided by the other.
Inverse rate: The same pair read the other way round: if one unit of the first currency buys X of the second, the inverse rate is 1 divided by X. It is the number you need when converting in the opposite direction.
Spread: The gap between the price at which a provider sells a currency and the price at which it buys. It is the provider margin, and it accounts for most of the distance between a reference rate and what you actually pay.
Currency pair: The two currencies in a quote, in reading order. In USD/INR the dollar is the base currency and the rupee is the quote currency, so the number answers "how many rupees to one dollar".
Base and quote currency: The base currency is the one worth 1 unit; the quote currency is the one the price is expressed in. Swapping them flips the number, and that is the most common mistake in currency conversion.
FX business day: A day on which the reference market is open. On Saturdays, Sundays and holidays there is no new rate: the last published one stands, and that is the one shown here.
Mid-market rate: The midpoint between the buying and the selling price at a given moment. Reference rates sit close to it, which is why they look better than any rate you are actually offered.
Bid and ask: The bid is the price at which a provider buys a currency from you; the ask is the price at which it sells to you. Travellers always pay the ask.