A margin call means...

Add money or positions get closed

Leverage: bigger wins, bigger losses

Leverage lets a small deposit control a much bigger position. It's like trading with borrowed money, and it cuts both ways.
At 1:100 leverage, US$1,000 of your money controls a US$100,000 position.
A 1% move in your favour: +US$1,000, your deposit doubled. A 1% move against you: −US$1,000, your deposit gone.
As losses eat your deposit, the broker issues a margin call: add money, or your positions are closed automatically, often at the worst moment.
Regulators limit it for beginners. In the EU, UK and Australia, retail traders get at most 30:1 on major currencies, 20:1 on gold and major indices, and 2:1 on crypto.
Common mistake
Mistake: “leverage makes me more money.” It makes you more exposed. The same small move that could double your deposit can erase it.
Key takeaway
Leverage multiplies gains and losses equally. Use little or none, and always with a stop loss.

Leverage multiplies... Both gains and lossesA bigger position means every price move counts more, in both directions.
At 1:100, a 1% move against you can... Wipe out your deposit1% of a position 100 times your deposit equals your whole deposit.
A margin call means... Add money or positions get closedYour deposit no longer covers the losses, so the broker demands more or closes trades.
In the EU, the maximum leverage on major currency pairs for retail traders is... 30:1Since 2018 EU rules cap it at 30:1 to protect beginners; the UK and Australia use the same limit.