Most of these commands result in text being pushed onto the kill ring so that it can be recovered. There is only one kill ring for all buffers so that text can be copied from one buffer to another.
Normally each kill command pushes a new block of text onto the kill ring. However, if more than one kill command is issued sequentially, and the text being killed was next to the previously killed text, they form a single entry in the kill ring (exceptions being Kill Region and Save Region).
Append Next Kill is different in that affects where a subsequent killed text is stored in the kill ring, but does not itself modify the kill ring.
Arguments: None
Key sequence:
Meta+D
Kills the rest of the word after the current point. If the current point is between two words, then the next word is killed.
Arguments: None
Key sequence:
Meta+Backspace
Kills the rest of the word before the current point. If the current point is between two words, then the previous word is killed.
Arguments: None
Key sequence:
Ctrl+K
Kills the characters from the current point up to the end of the current line. If the line is empty then the line is deleted.
Arguments: None
Key sequence: None
Kills the characters from the current point to the beginning of the line. If the current point is already at the beginning of the line, the current line is joined to the previous line, with any trailing space on the previous line killed.
Arguments: None
Key sequence:
Meta+K
Kills the text starting from the current point up to the end of the sentence. If the current point is between two sentences, then the whole of the next sentence is killed.
Arguments: None
Key sequence:
Ctrl+X Backspace
Kills the text starting from the current point up to the beginning of the sentence. If the current point is between two sentences, then the whole of the previous sentence is killed.
Arguments: None
Key sequence:
Ctrl+W
Kills the region between the current point and the mark.
Arguments: None
Key sequence:
Meta+W
Pushes the region between the current point and the mark onto the kill ring without deleting it from the buffer. Text saved in this way can therefore be inserted elsewhere without first being killed.
Arguments: None
Key sequence:
Meta+Ctrl+W
If the next command entered kills any text then this text will be appended to the existing kill text instead of being pushed separately onto the kill ring.