Create a booking Template

Google Forms
Typeform.com

For Hotels there are different kinds of CMS (Content management Services)
Bookfresh
Eventbrite - Copy and paste the html code into the blog to bring you to the site.

Widget or Gadget

ON FACEBOOK - docs

Wix.com

ADDTHIS.COM

Picmonkey.com

HTML Scripts are possible to find on any website. (Hyper Text Markup Language)

Go to Develop - Show page source/ to see whole html source coding.