Beginner

What is a render farm, and the types?

Talks about crowd rendered Render farms.  (like sheep it)

Use Garagefarm.net to render with a free 25$ credit.

Use the free cloud renderfarm using sheep it.

Intermediate

Intermediate skill but very easy.

 I put this Render Farm program in intermediate because normally you have to setup a lot to make a render farm.   No longer, this person's standalone renderer does everything, and standalone exe will allow you to render scenes on your computers.  Install the server file on the remote computers and run the Blendfarm.exe on your computer you're working on.   I tested several files and renders great. 

https://github.com/LogicReinc/LogicReinc.BlendFarm/releases    Very simple, install the files, run the server, and hopefully render one or more files.  This is great even for regular work because if you have a file with volumetrics or something that takes a while to render, having multiple computers working on the render saves you time on iterations of your work. 

List of different render services on the web.  Some paid.

Advanced

Blender Farm the stand-alone blender renderer.   Render your scenes on multiple computers.

Build your own computers for rendering. He shows how to setup several computers. Uses vnc to log into them. (vnc is a free program that takes control of a computer screen)
This video seems to use something in the older blender version. But the vnc part is good and can be used to log into your rendering machines.