Degrees of Comparison is used when we compare a person or thing with another. Degrees of Comparison is applicable only to Adverbs and Adjectives. Degrees of Comparison add variations to the sentences. A most familiar example of degrees i.e. good < better < best. The degree is increasing from good to best.
There are three degrees of comparison in English grammar.
A positive degree is used when we are talking about only one person or thing.
For instance, Jack is an intelligent boy. (Here the adjective intelligent describes the noun Jack. Also, the sentence talks about only one noun Jack) The Godfather is a good movie. Rose is a beautiful flower.
A comparative degree is used when we compare two persons or two things with each other.
For instance, Sam is more intelligent than John. (Here the adjective more intelligent describes the noun Sam whose intelligence is being compared to John’s intelligence. Also, the sentence talks about two nouns.) Captain America is as good as Iron Man.
A superlative degree is used when we compare more than two persons or things with one another. While using a superlative degree, keep in mind that you should always use the before it.
For instance, Jack is the most intelligent boy in class 7th. Joker is the best movie I have ever seen.
Take a look at how comparative and superlative are formed from positives. Few adjectives and adverbs get their comparative forms by adding more before and their superlative terms by adding most before them. Few adjectives and adverbs get their comparative forms by adding er after them and their superlative terms by adding est after them.
To sum up, Degrees of Comparison is used to compare one thing to another. The positive degree is used to describe one item or person. The comparative degree is used to describe two items or persons. And the superlative degree is used to express groups, more than two items, or person.