A lot of people know “你好“ (nǐ hǎo) as a greeting phrase in Chinese. I myself have been greeted many times in the street in Europe. Like “hello”, “你好“ (nǐ hǎo) is probably the most popular Chinese phrase known and used by foreigners.
However, do you know, actually there are a couple more greeting phrases in Chinese? Depending on the situation, different phrases should be used. Here I want to list some:
－－你好(nǐ hǎo) — Hello.
It is used in informal situations. It is used when addressing to one person. When used, no response is expected.
－－您好（nǐn hǎo) — Hello.
In formal situations, “您好” is used when addressing an elder person or a person at a higher rank.
－－你们好(nǐ mén hǎo ) — Hello.
This can be used in both formal and informal situations. It is used when addressing a group of people.
Sometimes you may hear “你好吗？” (nǐ hǎo mā?) which is a greeting question instead of a greeting, so an answer is expected. A typical answer is “我很好，谢谢，你呢？“ In detail,
－－你好吗？(nǐ hǎo mā?) — How are you doing?
—我很好，谢谢。你呢？（wǒ hěn hǎo. xiè xiè. nǐ nē?) — I am very well. Thank you. And you?
I hope it would be helpful to understand the difference.