The FBI's Data Intercept Technology Unit integrates with email and other Internet communication providers to implement wiretaps for accounts they have a court order for. They present the company with a court order, and the company forwards the account's data to the FBI (often via FTP, according to a New York Times article at the time). PRISM is simply a data integration project between the NSA and the FBI for ingesting data for accounts under a Section 702 order (for specific accounts belonging to non-citizens outside the US whose communications are of national security interest).
The FBI's Data Intercept Technology Unit integrates with email and other Internet communication providers to implement wiretaps for accounts they have a court order for. They present the company with a court order, and the company forwards the account's data to the FBI (often via FTP, according to a New York Times article at the time). PRISM is simply a data integration project between the NSA and the FBI for ingesting data for accounts under a Section 702 order (for specific accounts belonging to non-citizens outside the US whose communications are of national security interest).
It's right there on the leaked slide: https://imgur.com/setOJIm