A common dilemma that many traders face, especially beginners, is which price is more important to use when drawing a trendline?
Is the close price the most important price, or should we use the low price for an uptrend line and the high price for a downtrend line?
Well, for the close price advocates, I will confess that Charles Dow himself considered the close price as the most important price.

Please remember that Charles Dow lived in the 19 century when computers and automation were science fiction. Traders used to record prices on a piece of paper every day.
Nowadays, things are pretty different. Thanks to the advancements in technology, computers allow viewing prices in many ways and timeframes.
Additionally, all trading platforms provide not only the close price but also the open, high, and low price.
So, if prices decline to a lower level and then bounce off and close higher, what does it mean to us as traders?
My interpretation is that the market rejected the lower level for some reason, and prices moved and closed higher.
Or put differently, prices found support at the lower level and bounced up.
So, in this case, I would prefer to use the low price instead.
Similarly, if prices rise and then subsequently decline to close lower, what does it mean?

It simply means that high prices were rejected by the market as they found resistance.
And this is enough for me to use the high price instead of the close.