Leverage is the ability to control a large amount of capital using a relatively small amount of it.

For example, one lot of a currency pair has the value of 100,000 units of currency – 100,000 euros or 100,000 US dollars, and so on. Do we really have to have 100,000 euros or 100,000 US dollars in order to trade 1 lot of the EUR/USD currency pair?

No, we can control one lot, having only 1/200 of this amount. That is, we can say that the person who controls one lot of this currency pair uses a leverage of 200 to 1. The size of the leverage used by traders varies depending on their individual needs and their "comfort zone".