We use comparative adjectives to show change or make comparisons:
This car is certainly better but it’s much more expensive.
I’m feeling happier now.
We need a bigger garden
We use than when we want to compare one thing with another:
She is two years older than me.
New York is much bigger than Boston.
He is a better player than Ronaldo.
France is a bigger country than Britain.
When we want to describe how something or someone changes we can use two comparatives with and:
The balloon got bigger and bigger.
Everything is getting more and more expensive.
Grandfather is looking older and older.
We often use the with comparative adjectives to show that one thing depends on another:
The faster you drive, the more dangerous it is.
(= When you drive faster, it is more dangerous.)
The higher they climbed, the colder it got.
(= When they climbed higher, it got colder.)