Here we will try to explain the different choices you have in powering your robot limbs.
DC motors, stepper motors with rotary encoders, servos etc.
You need more powerul motors or servos to move things in a robots head like its eyes/eyelids/eyebrows and mouth and more powerful ones for moving arms and hands and even more powerful ones if you want actual leg movement.
For the head, inexpensive $20 small servo motors can do most of the work and can be hooked up to an arduino with software that you download from a website.
For the arms/legs you can either use rotational servos/motors or linear actuators (simple motor or the more expensive servo version).
Stepper motors which we explain in a different section are often good choices and can have great control but most hobbyists keep to using servos for almost everything for various reasons.
The linear actuator (go to a site like Actuonix) https://www.actuonix.com to learn more about your options here. The linear actuator looks like the strut rod that holds up your hatchback in your SUV truck or your porch back door but they are great to move an arm up and forward and back.
(under construction August 13,2021)