Can you set a static IP to a client machine from the router end?

I overheard a co worker mention a vendor had set a static IP on the router for a client machine. It caught me off guard and made me think about it, but the only thing I can think where you could do something like that would be to assign an IP based off of the MAC address.

Is something this possible or even best practice if the client is set to DHCP?

I honestly feel dumb for asking this, but I can't recall ever doing something like this before. I've always set the static on the client end, never the router end.

edit: Clearly I answered my own question :( Back to feeling dumb

Thanks everyone!