First, what is a MAC address and why might you want to alter, clone, or spoof it? MAC stands for Media Access Control and it’s a (theoretically) unique 12 hexadecimal digit identifier for a specific piece of network hardware. An example could look like 01-23-45-67-89-AB (remember hexadecimal digits range from 0 to F).
Now why might you want to spoof, clone or alter it? Some examples may include avoiding having to register a new router’s MAC address to an internet service provider, or to obfuscate a network monitor’s ability to tie traffic to a particular piece of hardware, or to circumvent a MAC address blacklist filter preventing a device from connecting.