What are comparatives and superlatives in English grammar?

[PercyColli]

I'm having trouble understanding how to use comparatives and superlatives correctly. Can someone explain the rules and give a few examples?

 

[SkyDrifter]

Things are compared by way of comparatives and superlatives.

Comparatives are used to compare two things and mostly they end in either -er or more.
For example, this book has less paging than this one.

Superlatives are used to compare three or more things and they usually end on -est or with most.
For example, this book is the shortest book in the world.