• Log isolates exponents, $log(2^3)=3log2$
• $log(xy)=log(x)+log(y)$
• $log(\frac{x}{y})=log(x)-log(y)$
• Log scale is used where there is fold change.
  I.e. 8 times greater than 1 is 8
  and 8 times less that 1 is 1/8
  But on the scale they are not same distance from 1
  But if we take log of them
  then $log(8)$ is 3 times greater from $log(1)$
  and $log(\frac{1}{8})$ is 3 times less from $log(1)$
  So the scale becomes comparable

Uses the logarithm to make fold changes comparable; see Log Normalization and Log (Odds).