Actor / Source
Who or what starts the event?
Meaning
The participant that acts, causes, initiates, controls, or is presented as the source of an event.
How to spot it
Ask who is doing, causing, or starting the event.
Examples
I|Peter|the dog|the machine|the wind
the teacher explains|the wind opens
The dog bit the postman.
Visual guide
ACTOR / SOURCE who starts the event? [the dog] -> bit -> postman [the wind] -> opens [the teacher] -> explains = doer/causer/source
Actor clues may differ order: [dog] bit postman case: [dog-NOM/ERG] agreement: dog -> verb pronoun form: I / me topic: [dog-TOP] voice: by [dog] role = event starter
Language View
In your language
In basic English clauses, the actor is usually before the verb and can trigger subject-verb agreement.
She opened the door.
she = the actor/source
In learning language
Actors are often nominative and reflected in verb agreement; explicit subjects can be omitted when the verb is enough.
كتب الطالب الدرس.
The student wrote the lesson.
Learners may rely only on word order and miss agreement or nominative marking.
Same block, different coding
Both languages use this block strongly, but they signal it differently. Focus on form changes, not only meaning.