A sums up a period, such as one trading day, and shows four prices: open, high, low and close. The wide runs from the open to the close, the thin reach up to the high and down to the low. Green means: the close is above the open. Red means: the close is below it.
What the body shows
A large green body means: at the end the price was clearly above the start. A tiny body, where open and close are almost the same, shows an undecided period. The color only tells you how the period ended – not how the next one begins.
What the wicks show
A long lower wick means: the price fell far in between but came back by the close. A long upper wick means the opposite. Our rule looks at the close: its trigger is a candle close above the last ; a wick above it is not enough.
One candle per period
The same prices make different candles depending on the period: a daily candle sums up one trading day, a 4-hour candle four hours, a weekly candle one week. The high of the weekly candle is the highest high of its days.