The NSA Warrantless Surveillance Controversy is about the National Security Agency (NSA) secretly collecting data on phones and computers. This means that the NSA has been gathering information like telephone numbers, locations, emails, and text messages from American citizens without first getting a warrant from a court allowing them to do this.
In short, the NSA was collecting information on people without their permission, which many people believe violates their privacy and the Constitution. This has caused a lot of controversy because people worry that the government is using this data to spy on them without their permission. Some people also think that it's not fair for the government to collect this data without getting permission from the courts first.