"اسم الفاعل" is a grammatical term in Arabic that refers to the "active participle." It is derived from a verb and indicates the doer of the action. For example, from the verb كتب (to write), the اسم الفاعل is كاتب (writer). This form helps to identify who is performing the action in a sentence. In Arabic, اسم الفاعل can also function as an adjective, describing a noun. It is formed by specific patterns depending on the verb's root. Understanding اسم الفاعل is essential for constructing clear and precise sentences, as it enhances the meaning by specifying the subject's role in the action.