Due to its vast linguistic diversity, the United Nations have made April 20th the Chinese Language day.
A thing you should know before visiting the country is that China does not refer to its languages as such, rather, they call them dialects. Despite the disagreement of linguists around the world, political reasons have made it so that they are referred to as such.
Chinese is also the world’s most common native tongue, being spoken by a grand total of 1.3 billion people. However, that is a bit disingenuous, as Mandarin speakers will be unable to understand, say Cantonese. The opposite, however, does not apply, as Chinese law makes it so that while cultural and regional autonomy might be permitted, those zones that do not have Mandarin as their native language will have to learn it as well.
There is a lot of linguistic debate on how many groups of Chinese languages there are, with numbers ranging from 7 to 10.