Left click refers to clicking the button on the left of your mouse. You would normally position your cursor in a chosen location on your screen before left clicking. Left clicking is normally used to select options on screen or to reposition the cursor . Also see right click.
To click the left most mouse button. Left clicking on an object normally executes a command.
This is when you press the left mouse button down once and release.
To press the left mouse button. This often initiates a command and can be the equivalent of pressing the Enter key on the keyboard.
To click the left button on the mouse. Usually used to select an icon. Also see Double Click.