Not every price chart adheres to the perfect exemplars of chart analysis, but sometimes they do.
Technical indicators include those that are purely mathematical in construction. A moving average crossover is an example. The crossover is a mathematical function that can be used to identify a change in market sentiment.
Then there is chart pattern analysis. The very best of patterns capture the psychological behavior of participants and provides an effective means to set a price target that has a high probability of being achieved. An up-sloping triangle pattern shows a sloping trend line (participants getting more eager) and a resistance level (existing stock holders with consistent selling at this level). The combination usually leads to a breakout.
The Guppy Multiple Moving Average indicator combines those two approaches and uses the mathematical calculation to make inferences about the way traders and investors are thinking. When their thinking agrees, then there is a high probability of a trend change developing.