In this video we go over the idea behind a basic IK system using the FABRIK algorithm. If you're interested in learning more the wiki page I wrote has a lot of information that was not covered in this video.
Wiki: https://developer.roblox.com/articles/Inverse-Kinematics-for-Animation
Place file: https://github.com/EgoMoose/ExampleDump/blob/master/Places/Inverse%20kinematics.rbxl
Thanks for watching! As always, hope you learned something new!