Sentences can be classified as
(1) simple, containing one clause and predication:
“John knows this country”;
(2) multiple or compound, containing two or more coordinate clauses:
“John has been here before, and he knows this country”;
(3) complex, containing one or more main clauses and one or more subordinate /dependent clauses:
“John, who has been here before, knows this country”
“Because he has been here before, John knows this country.”
Words like if, when, because, since, although, and many more, of course , are subordinating conjunctions which introduce subordinate/dependent clauses.
Subordinate clauses are dependent on the main clause in some way and do not normally stand alone.
Hope this helps;-)