A left mouse click is a fundamental action in computer usage. When you click the left mouse button, a few different actions can occur depending on where you click on the screen and what application or function you are using. In most cases, a left-click is used to select an item. For example, clicking on an icon on your desktop, a file in a folder, or a link on a website selects that item and opens it, so you can see it.
Holding down the left mouse button and moving the mouse is known as dragging. This action is commonly used to move files, resize computer windows, or interact with elements on the screen.