What is "if?

"if" is a conjunction used to introduce a condition or supposition. It is commonly used in English grammar to express the consequence of a hypothetical situation or to describe a possible event or situation. It is often used in conditional sentences, where one part of the sentence depends on the other. The word "if" is essential in constructing conditional sentences, which consist of an "if" clause and a main clause. Examples of sentences using "if" include "If it rains, we will stay inside" and "If I were you, I would go to the doctor."