What liquidity means
Liquidity describes how easily you can buy or sell an instrument without significantly moving its price. A highly liquid market has many buyers and sellers at almost every price, so your order fills quickly and close to where you expected.
Major currency pairs are among the most liquid markets in the world, which is part of why they have tight spreads. A thinly traded exotic pair or an obscure stock is far less liquid, and getting in or out can cost you noticeably.
How you feel liquidity
Liquidity shows up most obviously in the spread — the gap between the buy and sell price. Deep, liquid markets have narrow spreads; thin markets have wide ones. It also shows up in slippage: in a liquid market your order fills near the quoted price, while in a thin one it can fill several points away.
A concrete example: a major pair might cost you a fraction of a pip in spread, while an exotic could cost many pips. That difference is a real, recurring cost that quietly determines how hard your trades must work to profit.
When liquidity disappears
The dangerous truth about liquidity is that it is not constant. Around major news releases, market opens, or holidays, liquidity can thin out sharply. Spreads widen, prices gap, and stop-losses can fill far worse than expected — precisely when volatility is highest.
This is why trading straight into a big scheduled announcement is risky even if your direction is right: the market can move violently through your levels before you can react. Respecting liquidity means respecting the moments when it withdraws.