An emoji is a small picture or icon that you can embed right into your text to represent an emotion. If you are using Notepad in Windows and you want to add an emoji, press the Windows key and then the period. Select a happy face emoji and you will see the black and white version that’s similar to this: 😊

Since I am currently using WordPress, it will appear in color. When I am simply on the Windows desktop and I press the Windows key + . I will see the following popup.

For examples of emojis you can have a look at the emojipedia.org site or the microsoft section. For other platforms scroll down to the bottom of the page and select your platform on the left.