Subject

The subject is always a noun or a group of words that does the work of a noun.

Money is the root of all evil. (Here the subject is a noun.)
They refused to go. (Here the subject is a pronoun.)
The rich must help the poor. (Here the subject is an adjective used as a noun.)
To find fault is easy. (Here the subject is a to-infinitive used as a noun.)
Smoking is bad for health. (Here the subject is a gerund.)
Slow and steady wins the race. (Here the subject is a phrase.)

Attribute of the subjects

The subject is often qualified by an adjective or the equivalent of an adjective, which is called its enlargement or attribute.

The dog barked. (Here the attribute is an article.)
Fresh milk is wholesome. (Here the attribute is an adjective.)
The boy's face turned pale. (Here the attribute is a noun in the possessive case.)
Cromwell himself led the army. (Here the attribute is an emphatic pronoun.)
A rolling stone gathers no moss. (Here the attribute is a participle used as an adjective.)
Only his will to live pulled him through. (Here the attribute is a to-infinitive.)