Why is my printer not printing the entire document?

Check if the document is correctly formatted and of appropriate page size.
Ensure that no margins were specified in the print settings of the document.
If the document has been printed before with a specific set of parameters, try changing the page size and paper settings.
Check to make sure the printer is well connected to the computer and the computer is on.
Clean the dust off the printer if necessary.
Replace the toner or ink cartridges if required.
Restart the computer and printer to possibly clear up a software issue.