Digital rain is the famous effect on screen that the matrix created, with green letters falling and disappearing.
After some time with desire to replicate I tried to do so, but with only vanilla js and without Canvas, to practice a little bit of Javascript.
Not using Canvas makes it super heavy for the CPU, since it's moving DOM elements, and the conclusion I got to is if you want to do something move a lot in Javascript with a website it's better to do it in a canvas.