Boarding
This announcement is usually made while the aircraft is parked at the gate and the last passengers are boarding.
Door closure
Usually before the door is closed, or while it is closed, this announcement is made.
Safety demonstration
Depending on the type of aircraft and presence of a video system, this announcement will be made.
Take-off/ascent
Usually, the Captain will make a small briefing before take-off, sometimes indicating the priority for take-off (e.g. “We are third in priority for take-off, we should depart in about five minutes”). But there is always an announcement like
Turbulence
Occasionally, turbulence may occur during a flight. The seat belt sign will turn on and, in case of moderate to severe turbulence ahead, the flight crew will make a brief announcement.