(CNN) -- Government surveillance of telephone records and conversations in the name of national security has long been controversial.
The debate, which dates back decades, is back in the news with a report by The Guardian newspaper in England indicating that the FBI and National Security Agency obtained permission from a secret court to get call records involving at least some Verizon telephone customers.
Here's a primer on what the government is getting, how it affects you and what the legal debate is all about:
I'm a Verizon customer. What does the government know about my calls?
According to The Guardian newspaper, the National Security Agency and FBI are getting records on every call made by Verizon Business Network Services customers in the United States between April 25, when the order was granted, and July 19.
Details include each phone number involved in the call, details that identify the specific handsets being used, some general location information and the time and date of each call. Names, addresses and financial information is excluded.
It was not clear whether the order applies to all Verizon accounts or just those held by the Business Network Services subsidiary, or if other orders exist covering other units.
Can the government hear what I'm saying?
No. What appears to be a top secret court order published by The Guardian specifically excludes "the substantive content of any communication."
What if I'm not a Verizon customer? Does the government have my phone records, too?
While the order published by the Guardian includes only Verizon Business Network Services, the digital rights group Electronic Frontier Foundation says "it is very likely that business records orders like this exist for every major American telecommunication company, meaning that, if you make calls in the United States, the NSA has those records."
What happens to the records?
Sen. Dianne Feinstein, chairwoman of the Senate Intelligence Committee, said Thursday that the records go into a database and can't be accessed without "reasonable and articulable suspicion" that they're relevant to terrorist activity.
Why does the government need this information?
Access to such information "allows counterterrorism personnel to discover whether known or suspected terrorists have been in contact with other persons who may be engaged in terrorist activities, particularly people located inside the United States," a senior Obama administration official said Thursday.
The timing of the Verizon request -- coming less than two weeks after the Boston Marathon bombings -- has led to some speculation it could be linked to that investigation.
But Feinstein said the government has been collecting the records for seven years, renewing the authority every three months. The order published by The Guardian, she said, is a routine three-month renewal.
Who approved this?
It was OK'd by a judge for the Foreign Intelligence Surveillance Court, a special judicial branch set up as part of the 1978 Foreign Intelligence Surveillance Act. The court operates in secrecy, reviewing requests by intelligence agencies to conduct electronic surveillance and other activities as part of espionage, terrorism and national security investigations.
The request appears to have been granted under a section of the 2001 Patriot Act requiring private companies to turn over some business records as part of foreign intelligence or international terrorism investigations.
Is it legal?
The FISA Court judge who approved the request obviously thought so. But many privacy advocates and some lawmakers believe this sort of broad data collection goes too far.
"While I cannot corroborate the details of this particular report, this sort of widescale surveillance should concern all of us and is the kind of government overreach I've said Americans would find shocking," said Sen. Mark Udall, D-Colorado, who serves on the Senate Intelligence Committee.
In a letter last year to Attorney General Eric Holder, Udall and Sen. Ron Wyden, D-Oregon, complained about secret interpretations of the Patriot Act, details of which are classified but which the senators said "most Americans would be stunned to learn the details of."
"As we see it, there is now a significant gap between what most Americans think the law allows and what the government secretly claims the law allows," the senators wrote. "This is a problem, because it is impossible to have an informed public debate about what the law should say when the public doesn't know what its government thinks the law says."
Has this happened before?
In 2006, it was revealed that the NSA was secretly collecting telephone records as part of an effort to root out potential terror plots.
At that time, Verizon denied reports that it was providing the NSA with data from customers' domestic calls. The company said that while it is committed to helping the government protect against terrorist attacks, "we will always make sure that any assistance is authorized by law and that our customers' privacy is safeguarded."
The Electronic Frontier Foundation is also suing the NSA over claims that it was working with AT&T and possibly other telecommunications companies to suck up enormous amounts of Internet traffic through secure NSA-controlled rooms attached to network stations.
Other programs, some going back decades, have stoked similar concerns. In fact, abuses by intelligence services led to the passage of the Foreign Intelligence Surveillance Act in an effort to rein in domestic surveillance practices.