Vem is a modal text editor. That means that, at any given time, it can be in one of several possible modes. Each mode determines what is the action executed when each key is pressed. There are three main modes:
Normal mode: in this mode, the keyboard acts like a control panel. Each key is usually associated to a different command. For example, s saves the current file and . moves the cursor to the end of the current line. This is also known as command mode.
Insert mode: when typing in this mode, characters get inserted in the document as it happens in most conventional editors (most editors have this only mode). Only Ctrl key combinations, perform editing actions.
Visual mode: this is the mode that is active when there's a region of text selected. Some keys in this mode behave as they do in normal mode while others change their effect. For example, while movements are the same than in normal mode, many actions that affect a single line (like v to comment out code or e to copy text) in visual mode they affect the whole selection.
An additional mode is command-line mode that allows to execute commands in the last line of the editor, such as :sort to sort all lines in a document, or to provide search terms. Since this mode is a bit different from the other ones is explained in its own section.
During an editing session, it is very common to jump from one mode to another. You can change some parts of the document or move across its different parts in normal mode and then enter insert mode to add more text.
Changing modes is ones of the aspects that new users to modal editors take a bit of time to get familiar with. After all, most editors only have a single mode —what in Vim/Vem would be the insert one. Still is this multiplexing of the keyboard what makes this kind of editors so efficient. It allows the user to have a large amount of commands just at the fingertips and to edit text, quite literally, at the speed of typing.
After starting Vem, the editor is, by default, in normal mode. To start insert mode you can use:
start insert mode to the left of the current character
start insert mode to the right of the current character
To go back to normal mode use:
start normal mode
you can also use Esc, which is the key traditionally used in Vim. In Vem, however, the Ctrl-o combination is preferred because the position of Esc is much less comfortable than it was in the terminal where the original Vi editor was created (which, nowadays, would be the current position of Tab).
To start visual mode, you need to be in normal mode first. Then you can press:
start visual mode
Once in visual mode you can move the cursor to define the text selection that you want and operate over it using the visual mode commands (like e copy, d cut or c delete). The execution of many of these commands will put you back to normal mode. If you want to leave visual mode without performing any action (ie. deselecting the current selection), you can just press Ctrl-o or Space.
To make switching modes easier in certain situations, many commands perform an action and switch modes at the same time. For example, f deletes the word under the cursor and switches to insert mode. All these cases are explained in next sections of this guide.