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.
Q: I understand the capitalization rule for nouns, proper nouns require a capital letter. Also, I should begin a new sentence with a capital letter. When & why 'mom/dad' requires a capital letter ? (Reference- ELL- I am at Vapi where mom is hospitalised) mom: (n) informal term for a mother/North American term for mum.
A: 
When it is their name, Mom and Dad would be capitalised: Dear Mom and Dad, I am just writing to let you know, that although everyone has a mom and a >dad, you are my special mom and dad. So, Mom, I just want to say 'brava!'; and Dad, 'bravo!'. I've just been telling Sis, that Mom's new coat is so cool. XX Here's the commentary from an exercise from BBC English on Line ...to have a roast chicken lunch with my mother. I can't wait! - mother does not need a capital 'M' as it is not being used to replace her name. If I said, 'I am going to lunch with Mum', it would need a capital letter, but 'I am going to lunch with my mum' does not.