Let’s go reeeaaalllly slowly. First off: all (proper!) sentences need at least one clause. What on earth is a clause?
There are two types of clause:
Independent and dependent
Clauses are the core of a sentence, and every sentence needs to have at least one clause (if it’s to be a ‘proper’ sentence!).
An independent clause is the big brother, the king, the whole purpose of a sentence. It has a subject (The sun, I, you, he, she, it, we, they etc.), a verb (eats, walks, shines, sits etc.) and often a complement (usually a phrase adding more information either about the subject or the verb).
Subject Verb (Complement)
I am writing quickly before lunch.
I am thinking.
You should write something now.
An independent clause must express a complete a thought – however brief that thought – and be able to stand completely alone.
Just to make life easier, and you’ll begin to see this a lot in grammar, the independent clause is also known as a principal or main clause.