Adjective (Comparatives & Superlatives )

Comparative adjectives compare two things. Superlative adjectives compare more than two things.
Forming comparatives and superlatives:

One syllable (part)

Adjectives that have only one syllable (part) or adjectives that end in 'y' use ‘er’ to form comparatives and 'est' to form superlatives. For adjectives that end in 'y' change the 'y' to 'i' before adding 'er' or 'est'.
Old                older               (the) oldest
Young            younger         (the) youngest
Pretty             prettier            (the) prettiest
Long              longer             (the) longest
Short              shorter            (the) shortest
Happy            happier          (the) happiest
Close             closer             (the) closest

Two syllables or more

Adjectives with two syllables or more than two syllables do not change but instead have more in front of comparatives and most in front of superlatives.
Beautiful        more beautiful         (the) most beautiful
Amazing        more amazing          (the) most amazing
Horrible        more horrible           (the) most horrible
Expensive     more expensive        (the) most expensive
Delicious       more delicious          (the) most delicious

Different forms

Some adjectives have very different forms of comparatives and superlatives.
Good             better             (the) best
Bad               worse             (the) worst
Little              less                 (the) least
Much/many   more               (the) most
Far                further             (the) furthest

Than

We can use 'than' to compare two things.
Sarah is more intelligent than Peter.
Danny is quicker than his brother.
I have less free time than you do.

Using superlatives

Superlatives are usually used with 'the'
That was the best holiday I've ever had.
Paris is the most romantic city in Europe.
Peter is the oldest in our group.
You have the most beautiful eyes.
We took the shortest route to the station.