if

The word “if” means used to introduce a condition: supposing that something is or were true. In plain terms, introduces a condition — something that may or may not be true or may or may not happen.

“If” is pronounced ihf (/ɪf/ in IPA).

Here is “if” used in a sentence: “If it rains, we'll move the party indoors.”

Depending on how it is used, “if” can be a conjunction and a noun.

The word “if” comes from Old English. From Old English gif, going back to a Proto-Germanic word meaning "when" or "if.".

“If” is a very common word in modern English, usually learned at around the A1 level.

“If” has 3 distinct senses listed in this dictionary. The most common is: used to introduce a condition: supposing that something is or were true.

"If" introduces a condition ("If it rains, we'll stay in"), while "whether" introduces alternatives, especially after verbs like "know," "ask," or "decide" ("I don't know whether to go"). In formal writing, "whether" is preferred when two options are involved or before an infinitive.

Use "if I were" for situations that are imaginary or contrary to fact ("If I were rich, I'd travel"). "If I was" is used for real past possibilities ("If I was rude yesterday, I apologise"), though in casual speech many people use "was" for both.

When the "if" clause comes first, follow it with a comma: "If you're tired, go to bed." When the "if" clause comes second, no comma is normally needed: "Go to bed if you're tired".

"Unless" means "if ... not": "Unless you hurry, you'll be late" equals "If you don't hurry, you'll be late." Combining "unless" with another negative easily causes confusion, so most style advice is to keep "unless" clauses positive.