Mark Top Yanking
Most commands which erase text from the buffer save it in the kill
ring so that you can move or copy it to other parts of the buffer.
These commands are known as kill commands. The rest of the
commands that erase text do not save it in the kill ring; they are known
as delete commands. (This distinction is made only for erasure of
text in the buffer.) If you do a kill or delete command by mistake, you
can use the C-x u (
undo) command to undo it
The delete commands include C-d (
delete-backward-char), which delete only one character at
a time, and those commands that delete only spaces or newlines. Commands
that can destroy significant amounts of nontrivial data generally kill.
The commands' names and individual descriptions use the words `
delete' to say which they do.