Is it possible to use an iMac and a MacBook independently of each other but still display the same?

Is it possible to using an Imac and a Macbook independently of each other but still display the same? Would you be able to use your Imac and have those changes mirror to the Macbook and vice versa? Essentially eliminating the need to tether them and use them independently but have them mirror the same information?

[Re-Titled by Moderator]