When you see “GBP” or “USD” rather than “£” or “$”, you are looking at an ISO 4217 code — the international standard for naming currencies. Symbols are friendly but ambiguous (several countries use “$”); the three-letter codes are precise, which is why banks, trading systems and this site use them.
How the three-letter code is built
The structure is simple and consistent: the first two letters are the country’s ISO code, and the third letter is usually the first letter of the currency’s name.
- GBP = GB (Great Britain) + P (Pound). Note it is GB, not UK — the country code for the United Kingdom is GB.
- USD = US (United States) + D (Dollar).
The same logic gives EUR (a special case for the euro), JPY (Japan + Yen), CHF (Switzerland — “Confoederatio Helvetica” + Franc), and so on.
Symbols vs codes
The pound’s symbol £ comes from the Latin libra (a pound weight); the dollar’s $ has contested origins but is shared by dozens of currencies worldwide. Because “$” alone could mean US, Canadian, Australian or many other dollars, the unambiguous code USD is used wherever precision matters. Likewise GBP removes any doubt that you mean the British pound rather than another “pound”.
Numeric codes
ISO 4217 also assigns each currency a three-digit numeric code, useful in systems that cannot rely on letters. The pound is 826 and the US dollar is 840. You rarely see these as a consumer, but they appear in payment and banking infrastructure.
Why it matters for GBP/USD
The pair name “GBP/USD” is just the two ISO codes joined, base first: pounds quoted in dollars. Once you can read the codes, every quote on every platform becomes unambiguous — which is the whole point of the standard. For how the quote itself works, see how exchange rates work.