Answer:
It makes me warm and secure.
The buyer doesn’t want it, the producer doesn’t need it and the user doesn’t know their using it.
I start in little but I end in full, you'll find me in half and complete.
What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?
An art-form and its colourful result.
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?