WHAT ARE LINKERS ?

Linkers do not simply join sentences together. They also show how ideas are related.

"TO" -  Example -  Most people work to earn money.

"TO" infinitive is used here to express purpose. Also, IN ORDER TO and SO AS TO are used in formal situations.

Example : The government took these measures in order to reduce crime.

IF, UNLESS, IN CASE

These words are used to express a condition.

Example : You won't learn to use a keyboard properly unless you practice.

BUT, ALTHOUGH, INSPITE OF

These words are used to express the idea of contrast.

Example : The jacket was nice but it was too small for me.

BECAUSE , SO 

Because is used to express the reason for something while so is used to express the result of something.

Example : I turned the heater on because it was cold.

It was cold so I turned the heater on.