Vi editor have 3 working modes-
1) Command Mode
2) Input Mode
3) Ex Mode or Last Line Mode
Command Mode: It is starting mode of Vi editor. Commands are used in this mode of Vi editor.
For example, to copy, move text this mode is used.
Input Mode: ‘i’ key is pressed to switch from command mode to the input mode. Input mode made user able to enter the text in the file. ‘Esc’ key is pressed to go back to the command mode.
Ex mode or Last Line mode: To save the file in Vi editor ex mode is used. To enter in ex mode colon ‘:’ is types in command mode.