The lesson on YouTube
Watch. Then work through the idea.
Watch the English lesson first, then use the worked example and quiz below to check the idea. The article is a companion, not a transcript.
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What is actually happening?
The best bid is the highest displayed buy quote; the best ask is the lowest displayed sell quote. A market buyer normally meets available asks and a market seller normally meets available bids. A midpoint or last-trade chart can show a third number that is not reserved for your order.
Guided example · Frozen synthetic quotes · no live execution
Which price can a buyer meet?
Keep the two quote sides distinct from the midpoint and the plotted chart price.
Restart & example assumptions
Authored synthetic observations, shown in sequence. Every comparison uses only the revealed data. This is a worked learning example, not live prices, broker execution or a profitability backtest. Follow the article’s exact definitions; measurements and pattern names alone do not authorize a trade.
For charts: tap a candle or swing to inspect it; drag horizontally to browse; wheel or +/− to zoom; arrow keys to inspect; Home to restore the step view.
Make the conditions explicit.
Identify venue, instrument, timestamp and quote source. A displayed quote can change before an order arrives.
Before evaluating an entry, record the bid and ask together. Compute spread as ask minus bid, not as the distance from the chart’s last close.
Recheck if either quote changes or if the spread exceeds the filter you wrote before the setup. A stale snapshot is not an execution promise.
The quoted rules are illustrative research specifications. Parameters are not recommendations and have not been presented as profitable backtest results.
What can this cost?
Wider spread, commissions and slippage are separate cost components. Avoid counting the same cost twice when the fill assumption already incorporates the bid–ask difference.
How the idea can fail.
A midpoint chart at 100.05 can make a buy fill at 100.10 look like unexplained slippage. First establish which price the chart actually plotted.
Practical habit
Save both quotes next to the decision screenshot. A screenshot with only the last traded price cannot establish the spread.
Go one level deeper
Compare spread as a fraction of planned stop distance, not just in nominal cents. The same spread can matter very differently to two setups.
Check your understanding
Bid is 50.02 and ask is 50.08. Which pair is correct before quote changes or slippage?
Further reading & boundaries
These examples are original educational exercises. General background: CME Group: position sizing; Fidelity: technical analysis. Neither endorses these example rules. No hypothetical result establishes future profitability.
Editorial revision: 13 October 2026 · Synthetic data · Educational use