Creating files is all well and good, but eventually we'll come across a use case where the default permissions just aren't acceptable.
A good example of this is SSH, which will downright refuse to function unless some particularly rigid file permissions are in place on your public and private keys.
So, here come "The Three Musketeers", in the form of chown, chmod, and chattr.
If you want to be really annoying, and lose friends easily, insist on calling these by their full titles: change ownership, change mode, and change attributes.