Shortcut | Description | —— | —— | Ctrl + a | move to the beginning of the line | Ctrl + e | move to the end of the line | Ctrl + k | Kill the text from the current cursor position to the end of the line. | Ctrl + u | Kill the text from the current cursor position to the beginning of the line | Ctrl + w | Kill the word behind the current cursor position | Alt + b | move backward one word | Alt + f | move forward one word| Ctrl + Alt + e | shell expand line | Ctrl + y | Yank the most recently killed text back into the buffer at the cursor.| Alt + y | Rotate through killed text. You can only do this if the prior command is Ctrl + y or Alt + y.
Killing text will delete text, but save it so that the user can reinsert it by yanking. Similar to cut and paste except that the text is placed on a kill ring which allows for storing more than one set of text to be yanked back on to the command line.
You can find out more in the emacs manual.