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.
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Question: What do you call someone who knows all the gossip and stories about people in his neighborhood or surroundings, someone who's always informed. It doesn't have to be expressed in a word. Could be a sentence (e.g. she knows the ins and outs), but I'm looking for a better way to express it.

Answer: You could descirbe them as being in the know. While this often refers to someone knowing confidential information, it can also extend to someone who is just generally well informed. Collins Dictionary If you are in the know about something, especially something that is not known about or understood by many people, you have information about it.

Question: I keep writing dataset. Is that correct, or should I write data set?.

Answer: As @mmyers notes, dataset does not appear in any dictionaries. However, there are 172 incidences in the Corpus of Contemporary American English, and all but a handful are in the 'academic' section, representing formal academic writing. Its lack of appearance in dictionaries is probably because it is a fairly new coinage, the two examples from the Corpus of Historical American English are from 2001. Nothing from before then. Interestingly, the British National Corpus has 51 incidences, dating from the 1980s to the mid 1990s.

Question: I was googling the reason for why it's called 'shotgun' to ride beside the driver when it suddenly hit me - why on Earth is the firearm called 'shotgun'?! Is there any other kind of a gun than one used for shooting?! Why is it called 'shotgun' instead of just a 'gun' or a more technical term (9-gauge, barrel gun etc.)?.

Answer:
The 'shot' in shotgun refers to the ammunition that the gun fires. Whereas a pistol or rifle fires bullets (single metal balls), a shotgun fires a shell packed with shot (hundreds of tiny metal balls).