It's a type of present tense
A saxophone is used for playing music genres such as jazz and blues
IS USED FOR
Those activities are not continued in the present
Its negative form is DIDN'T USE TO
Subject + verb to be + Past Participle Verb + complement
Cellphones are made of plastic and glass. They're used for calling
Pandas are found in Asia
A chair is made of wood and it's used for sitting down
Notebooks are made of paper
A modal for activities in the past
The verb to be may vary according to the subject (singular or plural)
It has a contrast in the facts
The situations are not longer true
IS MADE OF
Subject + USED TO + infinitive verb + complement