A subject noun is the subject of a sentence and usually, but not always, comes before the main verb in a sentence. The subject performs the action described by the verb and can be identified in a sentence by the answer to the question "who did it?" or "what did it?" A noun is a name word used for a person, thing, animal, or something abstract and these nouns can function in a sentence as a subject, a subject or object complement, direct or indirect object, an adjective, adverb or appositive.
There are several ways a subject noun can be used. A subject can be partnered with an action verb such as play, eat or study. It can exist with a verb of "being" as in "is." For example, "There is a fly in my soup." A subject noun can be acted upon when used with a passive verb or described after a "being" verb or linking verb. An example of the latter is "This hamburger tastes delicious," where "taste" is the link between the subject and the adjective.
A noun is a part of speech and a subject is a word function in a sentence. Used together, a subject noun is the noun which is used as the subject in a sentence. Nouns are not always subjects and subjects do not always have to be a noun but most subjects are nouns, noun phrases or noun clauses. The basic parts of a sentence are the subject and the verb and these are usually accompanied by an object. Nouns can be subjects or objects. Basically, the subject gives a name to what the sentence is about, the verb is the "doing" or "being" word and the object is the recipient of the action dictated by the verb.
An object noun is usually found after the verb in a sentence. It is the person or thing that is affected by the action of the verb. A direct object is easy to identify as it answers the question "who or what is affected by or receives the action taken by the subject?" An indirect object is the noun or pronoun that is the recipient of the direct object and it is usually found before the direct object in a sentence. For example, "Emily gave her brother a present for his birthday." In this sentence, "her brother" is the indirect object and "a present" is the direct object.