What are the differences between key frames, blank key frames, and normal frames?

The key frame, that is, this frame is connected to two different contents. The video content after this frame will change or transition. On the timeline, this frame carries a small black dot sign;

A blank key frame has the same effect as a key frame, but this frame has no content. On the timeline, this frame has no small black spots. After this frame is filled with content, it becomes a key frame;

A normal frame is used to measure the playback time or transition time. You cannot manually set the content of a normal frame. It is automatically filled by the front and back key frames and transition types during the playback process, manual insertion or deletion of normal frames changes the transition time between the two key frames.