Comparative: when comparing TWO things
Short adjectives (1 or 2 syllables): add -er. 'Tall → taller'. 'Big → bigger' (double the consonant). 'Easy → easier' (y becomes ier).
'My brother is taller than me.'
Long adjectives (3+ syllables): use 'more' before. 'Beautiful → more beautiful.' 'Interesting → more interesting.'
'This book is more interesting than that one.'
Always followed by 'than': 'Bigger than'. 'More expensive than.'