A grammatical subject can be found in every well formed English sentence.
In a sentence, the subject is the thing (person, object, activity, place, etc.) which the sentence is about. The rest of the sentence tells us about the subject. In the examples below the subject is highlighted.
He ate a sandwich.
Mr Dowel danced.
Yesterday, the young boy gave the elderly woman a piece of chocolate.
Dancing is less popular than it was.
Every sentence in a properly formed English sentence has a subject. But the subject can take several forms.
Builders are at work. (a noun)
Next week she is travelling to Berlin. (a pronoun)
The large car stopped outside our house. (a noun phrase)
Eating is a pleasure. (a gerund)
To read is easier than to write. (an infinitive)
That he had travelled the world was known by everyone. (a clause)
'I love you' is often heard these days. (a citation)