Sixel is a protocal to display images in the terminal. You might be thinking about ascii art, but sixel is different; it looks the exact same as the image.
Sixel is just a bitmap image type, where a program just has to print out some specific text to make the image show up. Here is an example of sixel:
Some of you might be thinking about Ueberzug and how it works perfectly. If you did not hear the news yet, the maintainer of Ueberzug stopped maintaining it because they were being harassed by many people who wanted free support and updates as quickly as possible while not supporting the project in any way. Ueberzug was an amazing project that worked with almost all terminals, as it would create child windows and place them over your terminal.
Sixel is slowly getting more support. There is a website arewesixelyet.com that talks about all the terminals that support sixel.
Sixel is also not only for showing images; it can actually show gifs like this
These can be played in real time without slowing down. FFmpeg and Mpv even have support for Sixel, so you can watch almost any video in the terminal. We just need to wait for the TTY to get Sixel support, and then you will be the ultimate hacker man.