Expedia.com is built with the following tech stack:
Document Standards
HTML5 DocType
The DOCTYPE is a required preamble for HTML5 websites.
HTML 5 Specific Tags
This page contains tags that are specific to an HTML 5 implementation.
Content Security Policy
Content Security Policy is a computer security concept, to prevent cross-site scripting XSS attacks.
X-XSS-Protection
X-XSS-Protection is a HTTP header set by Internet Explorer 8+. This header lets domains toggle on and off the "XSS Filter" of IE8, which prevents some categories of XSS attacks.
Strict Transport Security
The HTTP Strict-Transport-Security (HSTS) header instructs the browser to only use https.
SSL Certificates
HSTS
Forces browsers to only communicate with the site using HTTPS.