As well as serving as modifying words like beautiful and big, adjectives are also used for indicating the position on a scale of comparison. The lowest point on the scale is known as the positive form, the middle point is known as the comparative form, and the highest point is known as the superlative form. Here are some examples:
This book is long. This book is longer than that book. This is the longest book.
The airport is far. The airport is farther than the train station. This is the farthest airport.
My mom is a good cook. My mom is a better cook than your mom. My mom is the best cook.
The comparative form
When two objects or persons are being compared, the comparative form of the adjective is used. The comparative adjective can be formed in two ways:
Adding –er to the positive form of the adjective.
Adding the word more before the adjective.
For example:
My essay is longer than yours.
She is more beautiful than her sister.