YouTube annotations is probably something that you may have noticed on YouTube videos lately, but never knew they were actually called 'annotations.' YouTube annotations are a new way to add interaction to your videos by using speech bubbles, background information about the video in the form of a text box, links to other YouTube videos or channels, or highlighting a certain part of a video containing text.
Every video on YouTube is able to utilize this feature, and when you are signed into your YouTube account, viewing your own video, you may see an edit feature on the lower left hand side, as well as in the Video Owner Options, called 'Annotations.'
Below is a great example of a video using Annotations. It's pretty neat how even over the internet, through video, you can perform magic tricks.
Here is another video on how to actually use YouTube annotations in your videos.
Learn more about adding YouTube annotations, and include a few on your YouTube video. It will definitely make an impact.