What is the pink fluffy stuff inside walls and roof?

insulation :)

insulation is used to keep eather heat or lack of it inside a building saving on heating and cooling costs. also some forms of it when contacted can cause one an itchy feeling.

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Agree. This type of insulation is usally called fiberglass. It is very fine strands of glass that resemble cotton. It is fireproof, does not rot, and bugs do not eat it. It does a good job of creating air spaces that limit movement of heat.