Subject
An element in the structure of a clause usually filled by a noun group, for example 'The dog (subject) was barking'. The subject indicates who or what gives agency or attributes to the finite verb or verb group and is usually found by asking 'who' or 'what' before the verb. In the sentence, 'The dog was barking', asking 'What was barking?' gives the answer, the dog. The normal position of the subject is before the verb group, for example 'The dog was barking', but in most kinds of interrogatives (questions) it follows the first auxiliary verb, for example 'Was the dog barking?', 'Why was the dog barking?' All main clauses and simple sentences must have a subject.