One of the things that makes Vim different from most other editors is that it has the concept of modes. For now, I just want to give you a quick overview of the modes. We'll be exploring each mode in depth in other lessons in the course. However, being aware that there are different modes and knowing what those modes are will really help you understand and learn Vim more quickly. When you start most editors, anything you type goes into the file or document that you're editing. That's not so with Vim. When you start Vim, you're actually placed into what is called normal mode. Some people refer to normal mode as command mode because anything you type at this point is interpreted as a command. By the way, it'll probably come as no surprise to you that Vim commands are case-sensitive, just as Linux and Unix commands are case sensitive. In order to send what you're typing into the document, you have to enter insert mode. There are a few ways to enter insert mode that you'll learn about later in the course, but the simplest way to enter insert mode is to press lowercase i. In insert mode, your keystrokes are not interpreted as commands. Instead, they are considered content for the file that you're editing. To leave insert mode and return to normal mode, press Escape. The last mode you should be aware of for now is line mode. Sometimes line mode is referred to as last line mode or even command line mode. To enter line mode from normal mode, type a colon. At this point, your cursor goes to the bottom line of your screen where you can type in a command and press Enter. You'll use line mode to perform various actions, such as saving a file, going to a specific location in the file, and turning on and off various Vim options and features. There are two ways to leave command mode. The first is after you've typed the command, you'll press Enter to execute that command. Once the command is completed, you're returned to normal mode. If you want to abandon the command, press Escape to return to normal mode. To review, there are three main modes in Vim. They are normal mode, sometimes called command mode, insert mode, and line mode. Keep in mind that you can always get to normal mode by pressing the Escape key. There are other modes in Vim, but they are really just slight variations on these three main modes. And don't worry, we'll be covering those other modes in the course as well. However, knowing about these three main modes will make learning Vim a lot easier going forward.