Posted with permission. Or it might be just a one page flyer. Depending on what the 'book' is about, you will find variation in size and content. There are sites which are strictly text, created to supply information specifically for others to read or download into their computers. Many businesses create web pages to advertise a product, and have security features that enable you to purchase products online.
Web pages can be quite interactive.
They may have moving graphics and sound bits. They may also have bulletin boards where 'surfers' can post messages directly from their own computers. There are sites with live conferencing via 'chat room' set-ups. Here you can have live conversations with others on-line. A major component of a web page are its 'links'.