Save and/or Save As

Save is used when:

It is the first time you are saving a file.
You want to keep saving a existing file in different moments that you are working on it.
It is the end of a working period.

Note that clicking Save will replace whatever file you were working on.

Go to File menu and select Save or use the combination keys CTRL+S.

Save As is used when you want to save a file with a different name to create backups of a file in the creation process. In that way, you can have different versions of the same document and can return to a previous stage.

Go to File menu and select Save As or use the combination keys CTRL+SHIFT+S.