You can’t publish anything which you want and do anything which you want and the forbidden publication or behavior is what is censored.
There are libelous publications which can unjustly ruin a human’s reputation and there is child pornography which most societies censor. In totalitarian countries political free expression is also censored and you can’t write articles criticizing the leadership. Profanity is also frequently censored in the public media.
There is no pure freedom of speech in society because publishing untruths or lies about someone who is not a public official can ruin a good reputation and severely hurt someone’s ability to make a living in society.
Military secrets are also censored which would compromise national security if they became public knowledge.
Government censors some political activities of government committees from the public where special deals are made favoring some special interests and this can be considered a bad form of censorship. Open source government would go a long way towards making government less corrupt but the politically powerful factions and politicians are generally against such sunshine public activity.
The internet is being censored to try and exclude criminal behavior such as terrorist plots and stealing of money, intellectual property, and identities. The censorship which is not so obvious is search engines with algorithms which favor information published by financially well off corporations and websites and exclude many small websites from easy access.
Search engines like Google and Bing are in fact powerful censors who have incredible control over what is published and how it is published frequently favoring the rich and powerful over the poor humans.
Privacy or keeping personal information from public view is becoming increasingly difficult if you use the internet. Soon your communications, medical records, and financial transactions may become public knowledge. Only the rich will be able to keep their lives private with encryption communications which will be harder to steal unless you are the NSA with government backing and have the ability to decode the communications.
Finally government tries to censor criminal behavior by passing laws which are then enforced by the legal system and police.
The rich and powerful will always find ways to keep their private information from public view through self-censorship. Whether common humans can maintain their privacy is an open question right now.
Censoring the internet to some extent is necessary but the real question is- Who will be in a position to censor and what kind of controls or safeguards will there be against unjust censorship by the rich and powerful financial interests and government?
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