Thanks to wikipedia for answering this question in simple terms. Here is the clear explanation:
The spot exchange rate refers to the current exchange rate. The forward exchange rate refers to an exchange rate that is quoted and traded today but for delivery and payment on a specific future date.
Quotations
An exchange system quotation is given by stating the number of units of "quote currency" (price Currency, payment currency) that can be exchanged for one unit of "base currency" (unit currency, transaction currency). For example, in a quotation that says the EUR/USD exchange rate is 1.2290 (1.2290 USD per EUR, also known as EUR/USD; see foreign exchange market), the quote currency is USD and the base currency is EUR.
There is a market convention that determines which is the base currency and which is the term currency. In most parts of the world, the order is: EUR – GBP – AUD – NZD – USD – others. Thus if you are doing a conversion from EUR into AUD, EUR is the base currency, AUD is the term currency and the exchange rate tells you how many Australian dollars you would pay or receive for 1 euro. Cyprus and Malta which were quoted as the base to the USD and others were recently removed from this list when they joined the euro. In some areas of Europe and in the non-professional market in the UK, EUR and GBP are reversed so that GBP is quoted as the base currency to the euro. In order to determine which is the base currency where both currencies are not listed (i.e. both are "other"), market convention is to use the base currency which gives an exchange rate greater than 1.000. This avoids rounding issues and Exchange Rates being quoted to more than 4 Decimal Places. There are some exceptions to this rule e.g. the Japanese often quote their currency as the base to other currencies.
Quotes using a country's home currency as the price currency (e.g., EUR 0.735342 = USD 1.00 in the euro zone) are known as direct quotation or price quotation (from that country's perspective) and are used by most countries.
Quotes using a country's home currency as the unit currency (e.g., EUR 1.00 = USD 1.35991 in the euro zone) are known as indirect quotation or quantity quotation and are used inBritish newspapers and are also common in Australia, New Zealand and the eurozone.
- direct quotation: 1 foreign currency unit = x home currency units
- indirect quotation: 1 home currency unit = x foreign currency units
Note that, using direct quotation, if the home currency is strengthening (i.e., appreciating, or becoming more valuable) then the exchange rate number decreases. Conversely if the foreign currency is strengthening, the exchange rate number increases and the home currency is depreciating.
Market convention from the early 1980s to 2006 was that most currency pairs were quoted to 4 decimal places for spot transactions and up to 6 decimal places for forward outrights or swaps. (The fourth decimal place is usually referred to as a "pip"). An exception to this was exchange rates with a value of less than 1.000 which were usually quoted to 5 or 6 decimal places. Although there is no fixed rule, exchange rates with a value greater than around 20 were usually quoted to 3 decimal places and currencies with a value greater than 80 were quoted to 2 decimal places. Currencies over 5000 were usually quoted with no decimal places (e.g. the former Turkish Lira). e.g. (GBPOMR : 0.765432 - EURUSD : 1.5877 - GBPBEF : 58.234 - EURJPY : 165.29). In other words, quotes are given with 5 digits. Where rates are below 1, quotes frequently include 5 decimal places.
In 2005 Barclays Capital broke with convention by offering spot exchange rates with 5 or 6 decimal places on their electronic dealing platform. The contraction of spreads (the difference between the bid and offer rates) arguably necessitated finer pricing and gave the banks the ability to try and win transaction on multibank trading platforms where all banks may otherwise have been quoting the same price. A number of other banks have now followed this.
While official quotations are given with the full number, for example 1.4320, many investors and analysts drop the integer for convenience and use only the fractional part, such as 4320. These are used frequently where a move in price is being described, for example 4320 to 4290 as opposed to 1.4320 to 1.4290.
If a currency is free-floating, its exchange rate is allowed to vary against that of other currencies and is determined by the market forces of supply and demand. Exchange rates for such currencies are likely to change almost constantly as quoted on financial markets, mainly by banks, around the world. A movable or adjustable peg system is a system of fixed exchange rates, but with a provision for the devaluation of a currency. For example, between 1994 and 2005, the Chinese yuan renminbi (RMB) was pegged to the United States dollar at RMB 8.2768 to $1. China was not the only country to do this; from the end of World War II until 1967, Western European countries all maintained fixed exchange rates with the US dollar based on the Bretton Woods system.
The "real exchange rate" (RER) is the purchasing power of two currencies relative to one another. It is based on the GDP deflator measurement of the price level in the domestic and foreign countries (P,Pf), which is arbitrarily set equal to 1 in a given base year. Therefore, the level of the RER is arbitrarily set, depending on which year is chosen as the base year for the GDP deflator of two countries. The changes of the RER are instead informative on the evolution over time of the relative price of a unit of GDP in the foreign country in terms of GDP units of the domestic country. If all goods were freely tradable, and foreign and domestic residents purchased identical baskets of goods, purchasing power parity (PPP) would hold for the GDP deflators of the two countries, and the RER would be constant and equal to one.
