Some comparison words are just special forms of adjectives: instead of describing one thing, they describe the relationship between two or more things.
For most adjectives, use the following guidelines when forming or using comparatives or superlatives:
used when comparing two things (including groups)
usually formed by adding “–er” to the end of the word: happier, softer, faster, taller
used when comparing more than two things
usually formed by adding “–est” to the end of the word: happiest, softest, fastest, tallest