"It" is necessary in this sentence to serve as the subject of the sentence. In English, pronouns are used as placeholders for nouns to avoid repetition and make sentences flow more smoothly. In this case, "it" is used to refer to the act of smiling, making the sentence clearer and more concise.
"It" is necessary in this sentence to serve as the subject of the sentence. In English, pronouns are used as placeholders for nouns to avoid repetition and make sentences flow more smoothly. In this case, "it" is used to refer to the act of smiling, making the sentence clearer and more concise.