what are the applications of thermal radiations?

Question

something like a technology that are used world wide other than thermal imaging

Answer 1

there are tons!
solar electricity generation.
solar water heaters.
solar anything really

Answer 2

I used to work in spacecraft thermal control. We'd have to have radiators that would point towards the dark part of space to radiate excess heat. There are radiators on the inside of the space shuttle payload bay doors.