Instructions: Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
Input: I'm a non-native English speaker, and my automatic spellchecker seems to accept both therefore and therefor. Is one orthography preferred ? Is that a British vs. American difference ? Or an old vs. more recent orthography ? Or something else ?.
Output:
Therefor means for that. For example: Here we sell guitars and accessories therefor. Therefor is one of a whole series of adverbs: thereof (of that), thereafter(after that), therein (in there), etc. If you are familiar with German - the Germanic sister of English - you can find a direct analogy there: for = fur therefor, for that = dafur (literally, therefor) Therefore, as you must know, means as a (logical) consequence