Although photography is ultimately about art, the use of high-tech gizmos inevitably leads to photographers throwing around an array of terms and acronyms that can be overwhelming to a new photographer. This list is (obviously) a work-in-progress, but I hope it'll help a bit!
Through The Lens. This typically refers to the ability of a camera to perform operations such as metering using the lens actually mounted to the camera at the time rather than using a secondary lens or sensor to accomplish these things.
TTL flash control -
A system of connecting a camera to one or more electronic flashes so that the camera's exposure metering and controls can be applied to control the power output of the flashes.