

It started with pop-up blockers.
Opera was the first major browser to incorporate tools to block pop-up ads; the Mozilla browser later improved on this by blocking only pop-ups generated as the page loads.[citation needed] In the early 2000s, all major web browsers except Internet Explorer let users block unwanted pop-ups almost completely. In 2004, Microsoft released Windows XP SP2, which added pop-up blocking to Internet Explorer. -Wikipedia
Those are good tips. Be aware though that they have multiple ways of tracking you (like screen size) and if you have a unique flight (e.g. departing from Boston arriving in Gary, IN on 4/29. Return on 5/5), they can figure it out.