The mechanism in plain terms.
A targeted ad does not appear by magic. A tracker, usually a small piece of code embedded in a page rather than the page's own content, notes that a particular browser visited a particular type of page. That signal is shared with an advertising network, which builds a rough profile of interests over time from many such signals across many sites, and later serves an ad matched to that profile on an entirely different site.
The gap between visiting a page and seeing a related ad elsewhere can be minutes rather than days, which is often what makes the process feel unsettling the first time someone notices it clearly happening. The speed is simply a sign of how automated the whole pipeline has become, not a sign that anything unusual has happened beyond the ordinary mechanics of ad targeting working as designed.
Where the signal comes from.
Cookies are the most common source, small files a tracker sets on a first visit and reads again on later visits, including on other sites that use the same advertising network. Account level tracking works even without cookies, since being signed into a search engine or a social platform lets that company link activity directly to your identity rather than to an anonymous cookie. Fingerprinting is the least visible method, quietly combining details like screen size, browser version and installed fonts into a signature that can identify a device without storing anything on it at all.
Turning off the parts you control directly.
Most major platforms offer an ad personalisation setting that limits how much of your activity feeds into their own targeting, found under the account's privacy or ads settings and worth switching off even though it does not stop tracking entirely on its own. Browser level tracker blocking, built into Firefox and Safari by default and available as an extension for Chrome and Edge, blocks a large share of third party tracking scripts before they load at all, which is often the single most effective step available.
What this genuinely changes.
None of this makes ads disappear entirely, sites still need some way to fund themselves, and a page will still show advertising either way. What changes is how closely matched that advertising is to your specific browsing, and how much of a profile accumulates behind it over months. Reading about companions filed under age 22 to 25 or age 30 and over, for instance, stops contributing to an advertising profile once tracking is limited this way, even though the page itself still loads normally.
Checking the settings a specific device or account offers.
On a phone, both major operating systems now offer a single toggle limiting ad tracking across apps rather than only inside a browser, an iPhone under Settings, Privacy and Security, Tracking, and an Android phone under Settings, Privacy, Ads, with an option to reset the advertising identifier entirely. This is worth doing on any device used for browsing near Amsterdam Noord or anywhere else, since app level tracking works alongside browser tracking rather than instead of it.
Judging when the effort is worth it.
Not every step here needs doing at once. Rejecting non essential cookies through the banner and switching off ad personalisation cost almost nothing and are worth doing as a baseline on every device. Tracker blocking extensions and a full review of app level tracking settings take slightly longer and are worth reserving for a device used for anything more sensitive, since the marginal benefit on a device used only for casual browsing is smaller.
A useful way to think about it: each additional step narrows the profile a little further, without any single one being strictly necessary on its own. Doing two or three consistently beats doing all of them once and never returning to check whether the settings have quietly reset after an update, which browser and app updates occasionally do without any clear notice that it has happened. Revisiting the same short list roughly twice a year is usually enough to catch anything that has drifted back to a default setting in the meantime, and pairing that check with the same season each time makes it far easier to remember without needing a separate reminder.
How this fits alongside a booking.
This sits closely alongside private search engines, since a search engine that does not track you removes one major source of the signal described above, and alongside cookie consent choices, since declining non essential cookies on the banner is the first and simplest step in the same direction. Checking our companions, confirming rates, or arranging an evening as couples works exactly the same however much tracking is switched off around it, and none of the steps above change how quickly a booking itself gets confirmed once a message is sent.