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PerformanceTerm

Pixel

tracking pixel · Facebook Pixel · VK Pixel · JavaScript tracker

Pixel is a JavaScript snippet on a website that records the actions of visitors and transmits events to the advertising platform.

A pixel is a small JavaScript code embedded on a website that tracks user actions (page views, adding to cart, purchasing, form submission) and transmits these events to the advertising platform - VK Pixel, Meta Pixel, TikTok Pixel. Based on this data, the platform builds retargeting audiences and trains the Smart Bidding algorithm.

Without a pixel, a performance campaign is like a car without GPS: it drives, but it’s unclear where. In projects, the first thing I do is check the correctness of the pixel installation through special extensions (Meta Pixel Helper, VK Pixel Helper) and compare the number of events in the platform with Metrica data. A discrepancy of more than 15% is a signal of a problem.

The main reasons for the pixel not working correctly: installed only on the main page (and not on all), blocked by adblockers (15–40% of users are blocked in different niches), conflicts with other scripts on the site, custom events are not configured (only the basic PageView). The latter is the most common problem in projects where the pixel “is” but does not actually count any orders or leads.

An alternative to the classic pixel is server-side tracking, which bypasses blockers and iOS restrictions. In 2025–2026, I am increasingly switching to server-based event transmission for large e-com projects.

Frequently asked questions about Pixel

What is a pixel?+
A pixel is a small JavaScript code on a website that records visitor actions: views, adding to cart, purchases, form submissions, and transmits these events to the advertising platform. Based on them, retargeting audiences are built and the optimization algorithm is trained.
How to check that the pixel is working?+
Through the Meta Pixel Helper or VK Pixel Helper extensions and checking the number of events with Yandex Metrica. If the discrepancy is more than 15%, there is a problem: the pixel is not on all pages, it conflicts with other scripts, or custom events are not configured.
Why doesn't the pixel see some of the conversions?+
The main reasons: ad blockers cut from 15 to 40% of events depending on the niche, iOS and ITP restrictions in Safari, installing a pixel only on the main page and the lack of custom events. The solution is server-side tracking, transmitting events from the server bypassing blocking.
Pixel or server-side tracking?+
For a small site without a developer, a pixel with improved compliance is sufficient. For large e-coms, I switch to server-based event transmission: it bypasses blockers and iOS restrictions and usually increases the number of visible conversions by 25-40%.

Related terms

Server-side TrackingCustom AudienceSmart BiddingCPA

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