Conjunctions connect words, phrases, or clauses. Examples include:
* And, but, or, so, yet, for
"If" is a subordinating conjunction, which introduces a dependent clause. A dependent clause cannot stand alone as a sentence. It needs an independent clause to make a complete thought.
Here's an example:
* If you study hard, you will succeed.
"If you study hard" is a dependent clause. It relies on the independent clause "you will succeed" to make sense.
In short: "If" is a subordinating conjunction that introduces a dependent clause, making it part of a complex sentence.