When do I use "if" and "whether"? Could anybody, please, help me with this? I know that "if" is used to indicate condition and "whether" is used when presenting different alternatives. But I've noticed that, many times, "if" is also used to expose distinct options, like "whether". So my question is: are there any rules that determine which of them should be used when presenting different alternatives? Or are they simply interchangeable in this case? What does the English grammar say about this? Thank you in advance! :D