In narrow sense, all of the personal information such as ID card or social security number are considered private. No one has the power to share your information without your permission. For corporation or government, the secrets of the business or the country are always considered private. No individuals or social media can share the privacy in public.
In broad sense, what I said above is not absolutely correct. Most often, for the public safety, the government system must share the personal information to the bank or the employer. It’s impossible to keep all of your data definitely private. If you insist to do it, you are not allowed to do anything in public. Therefore, no matter the information is absolutely given away freely or not, there is also a big problem with either corporation or government reviewing published information. The social order will be in havoc. Actually, keeping private or sharing in public are just comparative terms. Keeping private is based on the actual situation.