An e-book, or 'electronic book' is just what it says it is - something you read on screen instead of on paper.

You can load books onto small computers like PDAs to read while you're on the move.

So, next time before you get on the bus you can download that thriller or romance e-book rather than read the newspaper of the person next to you.

A lot in the name

There are lots of different things called 'e-books'.

Some are actually computers and may even be leather-bound to resemble real books!

Others are just computer programs which can read and display special types of files. You use these on your desktop or laptop computer.

E-book pluses

An e-book can give you lots more than a paper book. You can store lots of books on one computer, for example. You can mark your page with an electronic bookmark and jump straight to it when you open the book.

Some e-books have built in dictionaries so you can click on a word and find out what it means. And non-fiction books may come with extensive collections of references and footnotes.

And of course an e-book does not have to be just words; it can include pictures and even sound clips and video or animated graphics.

It is possible to read an e-book on your desktop or laptop computer.

They do a reasonable job of displaying text and images but lack some of the features we normally associate with books - like portability and instant access.

E-book hardware

There are special purpose e-book devices like the RocketBook, which are dedicated to displaying 'pages'.

They are portable, have a much larger capacity than a book of comparable weight and size, offer good battery life and usually have high-resolution displays.

However, they are limited to the book formats supported by the manufacturer; they have to be connected to a 'proper' computer to download texts or manage libraries and are not easily extensible.