A participle is a verb form used as a modifier. Participles usually end in '-ing' or '-ed'. The word 'fallen' is a past participle used as an adjective in:
The logger jumped over the fallen log.
Participles can also be used with auxiliary verbs to form compound tenses. The past participles in the next sentences indicate a past action or state:
The log had landed before I arrived
Superman had saved the day!
A present participle indicates an ongoing action or condition:
I am swimming in air.
The sun is shining brightly.
'Speeding' is a present participle used as an adjective in:
Superman caught the speeding train.