system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When people talk about "rendering" a video for x amount of time, what is the process that is taking place?

Do they leave the computer turned on until the video renders? What about a video that takes weeks, or even years?
gpt
Basically the computer program needs to calculate what exactly will appear on each point of the screen, for each frame. It needs to take into consideration the objects that are in the scene, their location and appearance (colors, textures etc.) and especially the lighting.

> Do they leave the computer turned on until the video renders? 

Yes.

> What about a video that takes weeks, or even years?

Each frame of the video can be rendered separately. This allows the rendering process to easily split to multiple computers on a server farm - instead of having one computer work for 5 years, you can have 100 computers work for two and a half weeks.