An after action report was a written report used by the United Federation of Planets following important events or conflicts.
In 2257, after Christopher Pike seemingly allowed Leland to beam Michael Burnham and Spock up from Talos IV, he told him he had done the right thing and he would note it in his after action report. (DIS: "If Memory Serves")
Worf submitted an after action report following the disastrous Klingon attack on Avenal VII in late 2375. In the report, he detailed that seven Klingon starships had been destroyed, five more were heavily damaged and that General Martok had been injured and was being treated in the Rotarran's sickbay.
Later, Captain Benjamin Sisko angrily confronted Chancellor Gowron with the report. (DS9: "Tacking Into the Wind")