What is お in お元気ですか?

Question

Sorry if this is a very basic question, but I'm trying to understand everything in my first lesson (online, Rocket Japanese). I don't understand what the purpose of お is in the phrase お元気ですか, which is explained as how I ask someone how they are. I believe 元気 refers to well-being or health, です is roughly the verb "to be," and か is added to turn the phrase into a question. But nowhere is お explained. Is it actually required, and if so, what does it add to the question? On the site it is translated to "how are you?"

Answer 1

お and ご, both represented by the kanji 御, are prefixes that increase the politeness of a word. They are often used when referring to other people to put them on a higher level than yourself, which is why you say 「お元気ですか」 to other people, but you say 「元気です」 about yourself.

Whether you use お or ご is dependent on the word, so ご元気 is not correct. お usually goes with 訓読{くんよ}み readings and ご with 音読{おんよ}み readings. (source) This rule is already broken by the word 元気; fortunately the kanji 御 is rarely used, so you usually don't have to guess which one it is when reading.

In addition, there are certain words that usually have お/ご on the front, such as alcohol (お酒{さけ}). Some words require it, or would change in meaning or reading without it, like sorry (御免{ごめん}), rice/meal (ご飯{はん}), stomach (お腹{なか}), and money (お金{かね}).