How did the tradition of trick or treating start?

It originated from a ritual that involved people dressing up as ghosts,demons and monsters. They would dance around a bonfire. They also received treats.

Explanation:

It was basically a pagan ritual.

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productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.