I don't know how 'easy' you can make it and still be inclusive, Guest, but a participle is just the name for a non-finite (no tense) verb form ending in -ing or -ed/-en, and used either (1) as an adjective (the tired employee, the running deer) or (2) as part of a periphrastic (multi-word) finite verb (has been tired, will be running). That is essentially all there is to a participle.
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