Comparison Of Adjectives

Read these sentences:

1. Peter's mango is sweet.
2. John's mango is sweeter than Peter's
3. Lisa's mango is the sweetest of all.

In sentence 1, the adjective 'sweet' merely tells us that Peter's mango has the quality of sweetness, without saying how much of this quality it has.
In sentence 2, the adjective ' sweeter ' tells us that John's mango, compared with Peter's, has more of the quality of sweetness.
In sentence 3, the adjective ' sweetest ' tells us that of all these mangoes Lisa's mango has the greatest amount or highest degree of the quality of sweetness.
We thus see that Adjectives change in form ( sweet, sweeter, sweetest ) to show comparison. They are called the three Degrees of Comparison.
The Adjective ' sweet ' is said to be in the Positive Degree.
The Adjective ' sweeter ' is said to be in the Comparative Degree.
The Adjective ' sweetest ' is said to be in the Superlative Degree.
The positive degree of an Adjective is the adjective in its simple form. It is used to denote the mere existence of some quality of what we speak about. It is used when no comparison is made.
The comparative degree of an adjective denotes a higher degree of the quality than the positive, and is used when two things ( or sets of things ) are compared; as, This boy is stronger than that.
.The superlative degree of an adjective denotes the highest degree of the quality, and is used when more than two things are compared; as,  This boy is the strongest in the class.