A break is usually defined as a close beyond the line rather than a touch, because intrabar pokes through a hand-drawn line are routine. Some traders require a close beyond by a fraction of atr to filter noise.
A broken trendline does not mean reversal. It most often means the trend's angle has changed: a steep line breaks and a shallower one takes over. Reading every break as a top is one of the most common beginner errors.
More useful is to pair the break with structure. A trendline break plus a lower swing-low on the same chart is a break-of-structure, and that combination has far more information in it than the line alone. The break on its own is a prompt to look, not a signal to trade.
Related: trendline, break-of-structure, change-of-character, false-breakout, confirmation-signal