Q: I created a flash book, but which format I can use to send to my friends via Emails?

HTML: allows you to upload to a website to be viewed online;
EXE: output as a standalone file which can be viewed simply in local computer;
ZIP: used to send eBooks in Zip package to others by email.

So, you can choose "*.zip" if you want to send your created flash book to others, then attach outputted ZIP file in emails to send out with ease. Your receivers just need to download and decompress the ZIP package, with opening the HTML to view your eBook in browser.