Explain the difference between ITCSS and SMACSS.

ITCSS organizes CSS by specificity via an 'Inverted Triangle', while SMACSS organizes by categories (Base, Layout, Module, State, Theme).

ITCSS (Inverted Triangle CSS) dictates the order of CSS files from least specific (resets, variables) to most specific (utilities/trumps) to prevent specificity wars. SMACSS is a categorization strategy to componentize logic. They can be combined effectively.