On a log scale the axis is spaced by ratio. That matches how returns actually work: a $1 move matters far more on a $5 stock than on a $500 one.
Log scaling changes the geometry of trendlines. A stock compounding at a steady percentage rate plots as a straight line on log and as a curve that accelerates upward on linear-scale. Long-term charts, crypto histories and anything that has multiplied several times should be viewed on log, or your trendlines will be nonsense.
Example: Bitcoin from $1,000 to $60,000 on a linear chart compresses years of history into a flat line at the bottom. On log, the 2013 and 2017 cycles are legible. For intraday charts spanning a few percent, the two scales are visually identical.
Related: linear-scale