Fraud & invalid traffic · also called Automated browser
Headless browser
A headless browser is a real web browser run by a program with no visible window, able to load pages and click exactly as a person's browser would.
Developers use headless browsers every day for honest work: testing websites, taking screenshots, checking that pages load. The browser runs on a server with no screen, driven by a script.
The same tool is the workhorse of modern bot traffic. Because it is a genuine browser, it runs the page's code, loads the related-search unit, fires the ad request and can click a sponsored listing. A basic script that only fetches pages could never do that. Fraud operators add patches to hide the traces of automation and pair the browser with a residential proxy.
Still, automation leaves marks. The browser may report properties that a hand-driven browser would not, miss features real devices have, or behave with machine regularity: no idle time, perfectly straight pointer paths, identical delays. Collecting such signals is part of device fingerprinting and behavioural analysis.
For arbitrageurs the relevance is simple. If a traffic source's visitors are headless browsers, every cent paid for them is wasted and every feed click they make is an invalid click that someone will eventually have to repay.
Think of it like this
It is a self-playing piano. Real keys move and real notes sound, but nobody is sitting on the stool.
Related terms
Bot traffic
Bot traffic is visits and clicks made by software instead of people, ranging from harmless crawlers to programs built to imitate real users.
Device fingerprinting
Device fingerprinting identifies a device by combining many small technical traits, such as screen size, fonts and browser version, into one recognisable signature.
Data-center traffic
Data-center traffic is visits that originate from servers in hosting facilities and cloud providers, where programs run, not from homes or phones where people browse.
Residential proxy
A residential proxy routes someone's internet traffic through an ordinary home connection, so a bot or distant operator appears to be a normal household user.
SIVT (sophisticated invalid traffic)
SIVT is invalid traffic designed to look like real people, which can only be found with advanced analysis that compares many signals at once.
Sources: MRC Invalid Traffic Detection and Filtration Standards Addendum (June 2020 update), Google Ads Help: Invalid clicks, definition