If you have come from traditional odds formats, the first thing to know is that a prediction market price is just a percentage. There is no fraction to convert, no decimal to multiply. 30% means the crowd rates it about 30% likely. That is the whole language.

From probability to payout

The payout on a winning position is roughly 1 ÷ probability. Some useful reference points:

10% pays about 10× — an outcome the crowd thinks is unlikely.
25% pays about 4×.
50% pays about 2× — a genuine coin flip in the crowd's view.
75% pays about 1.33×.
90% pays about 1.11× — you are backing the strong favourite, so the reward is small.

Those figures are the shape of the relationship, not a promise: the exact quote you see already includes our margin, and it is shown to you before you confirm. The point of the table is intuition — a price tells you both how likely the crowd thinks something is and what it pays, at the same time.

YES and NO are two views of one number

If YES is trading around 30%, NO is the other side of the same question. Backing NO means backing the far more likely outcome, so it pays much less. There is no "better side" — there is only whether the price is right.

The only question that matters: is the price wrong?

Write down your own probability before you look at the market. If you would give an event 60% and the market says 45%, you have a 15-point edge and the YES side is interesting. If your number matches the market, there is no trade — however strongly you feel about the outcome.

This is the habit that separates trading from guessing. A favourite at 90% can be a great trade if you think the true number is 97%. An outsider at 5% can be a terrible one if you think the true number is 2%.

Read the whole market, not just the number

The close time. A long-dated market has more time for your thesis to break.
The resolution source. If you do not recognise it, treat your estimate as less reliable.
The gap between the two sides. A wide gap means thin interest: your entry costs more and so does your exit. See reading the YES/NO spread.
How much size sits behind the price. A big order in a thin market fills worse than the headline number.

Common misreadings

"10% means it cannot happen." It means roughly one time in ten. Long-shot markets resolve YES regularly.
"A big payout is a good bet." The payout is large because the outcome is unlikely. The two always move together.
"The price jumped, so I have missed it." Maybe — or the move overshot. Form your own number and compare.
"The crowd is wrong because I disagree." Sometimes true, which is why markets are tradeable. Size accordingly: see sizing trades by edge.

Practise on something you know

Pick a subject you follow closely and read the prices before you trade anything. Sports, politics, economy and entertainment markets are all priced the same way — only the subject changes.