What is the relationship between different currency pairs? factors depends the value of a currency?

In case of EURUSD and  GBPUSD in both of the first two currency pairs (EURUSD and GBPUSD), USD works as the money. As you know, the first currency in currency pairs is known as the commodity and the second one is the money. So when you buy EURUSD, it means you pay USD to buy Euro. In EURUSD and GBPUSD, the currency that works as the money is the same (USD). The commodity of these pairs are both related to two big European economies. These two currencies are highly connected and related to each other and in% of the cases they move on the same direction and form the same buy/sell signals.

There are different factors on which currency value depends like inflation rate, interest rate, demand and supply.