Support and resistance are horizontal — flat levels price keeps reacting to. A trendline is the diagonal version of the same idea: instead of a flat price, it's a rising or falling line connecting points where price has repeatedly reacted, as the overall level itself shifts over time. It's a genuinely useful tool, and also one of the easiest to draw badly without realizing it.
What a trendline is actually connecting
In an uptrend, a trendline connects a series of swing lows — the points where each pullback found buyers before pushing higher again. In a downtrend, it connects swing highs — the points where each rally failed before rolling back over. The line itself isn't the important part. What matters is that it's connecting real points where price genuinely reacted, not just any two points that happen to line up conveniently.
You need at least two points to draw a line at all, but a trendline doesn't really earn credibility until a third point touches it too. Two points can always be connected — that's just geometry. A third point actually reacting at that same line, without being forced to fit, is the first real evidence the line means something.
The mistake almost everyone makes early on
New traders often draw a trendline the other way around: they decide what direction they want the line to show, then adjust the angle until it roughly fits the points they want it to touch, ignoring the wicks or swings that don't cooperate. That's forcing a narrative onto the chart, not reading one off it. A trendline drawn honestly should connect real swing points cleanly — if you're tilting the angle repeatedly to make it "work," it's not actually describing what price is doing.
Channels — the trendline's other half
A channel is just a trendline with a second, parallel line drawn on the opposite side — one connecting the swing lows, one connecting the swing highs, running roughly parallel to each other. Together they define the rough zone price has been oscillating within during a trend: the lower line acts like a dynamic support level, the upper line like dynamic resistance, both angled with the trend instead of sitting flat.
Trading a trendline break
The same caution that applies to any breakout applies here: price briefly poking through a trendline isn't the same as a real break. A single wick crossing the line and snapping back is far weaker evidence than a full candle closing clearly beyond it, and — same principle covered elsewhere — that break means more if it holds up on a higher timeframe too, not just the chart you happened to draw the line on.
The honest part
Trendlines are genuinely subjective. Two traders looking at the exact same chart will often draw slightly different lines, connecting slightly different swing points, and both can have a reasonable case for their version. That doesn't make the tool useless — it makes it a directional guide, not a precise, objective level the way a calculated pivot point is. Use it to read the general structure of a trend, not as a line so exact that a single pip on either side changes the entire read.
SonaPips itself doesn't trade off hand-drawn trendlines — its method looks at whether price actually breaks and holds beyond the Asia session's range on Gold, EUR/USD, and GBP/USD, confirmed on a higher timeframe rather than a line someone drew by eye. Different tool, same underlying question: is this move real, or does it just look real for a moment?