The units of measurement to express the change in value between two currencies are called a “pip.”
PIP
If GBP/USD moves from 1.2105 to 1.2106, that .0001 USD rise in value is ONE PIP.
Movement in the exchange rate is measured by pips. Traders often use the term “pips” to refer to the spread between the bid and ask prices of the currency pair and to indicate how much gain or loss can be realized from a trade.