O-Books, or online books, are digital versions of traditional printed books that can be read on various devices such as computers, tablets, and e-readers. They offer the same content as physical books but provide added features like adjustable font sizes, search functions, and hyperlinks to additional resources. These books can be purchased or borrowed from online platforms, making them easily accessible to a wide audience. O-Books often come in formats like PDF, ePub, or MOBI, allowing for compatibility with different reading applications. This digital format has transformed how readers engage with literature and information.