The subject may consist of one word or several words, but it must always have a noun in it. This noun, which is the most important word in a sentence, is often qualified by an adjective or other modifiers which are called its attribute. The attribute of a noun may be an adjective, an article, a pronoun, a participle, an infinitive or a phrase.
The girl smiled. – the attribute is the definite article the;
A man with dark hair passed by us not so long ago. – the attribute is the indefinite article a;
Fresh food is the healthiest. – the attribute is the adjective fresh;
His voice was shaking. – the attribute is the possessive pronoun his;
Kennedy, President of America, was assassinated. – the attribute is the noun phrase President of America;
He himself said this. – the attribute is the reflexive pronoun himself;
A rolling stone gathers no moss. – the attribute is the participle rolling;
Birds of the same feather flock together. – the attribute is the prepositional phrase of the same feather;
His will to live pulled him through the difficult times. – the attribute here is the infinitive to live.