Alternatively called documentation or end-user documentation, a manual is a book or pamphlet containing information about a program or piece of hardware. For example, a computer case may come with documentation explaining what sizes of motherboard it can hold. Or, a video game may come with a manual explaining how to play it.
Today, most manufacturers and developers no longer include printed manuals with their products. They instead rely on electronic documentation and online documentation, which are usually included as a PDF (Portable Document Format) or available for download on the manufacturer's website.