Short answers, pulled from the story.
Privacy is the ability of an individual or group to seclude themselves, or information about themselves, and thereby express themselves selectively. The word derives from the Latin privatus, meaning things set apart from what is public, personal and belonging to oneself rather than to the state.
Samuel Warren and Louis Brandeis wrote The Right to Privacy, an 1890 article generally regarded as the first American publication advocating privacy. They argued for a right to be let alone, written largely in response to the rise of newspapers and photographs.
In 2018, the Supreme Court ruled in Carpenter v. United States that the FBI's warrantless use of Timothy Ivory Carpenter's cell phone records violated the Fourth Amendment. The court held that information sent to third parties can still fall under reasonable expectations of privacy.
John Locke argued in his 1689 Second Treatise of Civil Government that government must protect each person's natural rights to life, liberty, and property, guaranteeing private spaces. John Stuart Mill, in his 1859 essay On Liberty, treated privacy as essential to personal development and self-expression against the tyranny of the majority.
Digital ad brokers such as Facebook and Google encouraged behavioral advertising that tracks users through HTTP cookies, with data sold into a mass surveillance industry. Data brokers planted inside apps built a 350 billion dollar industry focused on mobile devices, and four spatio-temporal points can uniquely identify 95 percent of people in a mobility database.
David Attenborough, a biologist and natural historian, said gorillas value their privacy and that viewing them through glass enclosures violates that right because they know they are watched but cannot control it. Overcrowding that removes animal privacy has been linked to heart disease, high blood pressure, and higher infant mortality.